diff --git a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/DTDErrorCode.java b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/DTDErrorCode.java
index dffa147600..e486160dec 100644
--- a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/DTDErrorCode.java
+++ b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/DTDErrorCode.java
@@ -24,6 +24,7 @@
 import org.eclipse.lemminx.dom.DOMRange;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.ElementDeclUnterminatedCodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.EntityNotDeclaredCodeAction;
+import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.FixMissingSpaceCodeAction;
 import org.eclipse.lemminx.extensions.contentmodel.participants.codeactions.dtd_not_foundCodeAction;
 import org.eclipse.lemminx.services.extensions.ICodeActionParticipant;
 import org.eclipse.lemminx.services.extensions.diagnostics.IXMLErrorCode;
@@ -36,7 +37,7 @@
 
 /**
  * DTD error code.
- * 
+ *
  * @see https://wiki.xmldation.com/Support/Validator
  *
  */
@@ -67,6 +68,9 @@ public enum DTDErrorCode implements IXMLErrorCode {
 	MSG_NOTATION_NAME_REQUIRED_IN_NOTATIONDECL, //
 	MSG_OPEN_PAREN_OR_ELEMENT_TYPE_REQUIRED_IN_CHILDREN, //
 	MSG_REQUIRED_ATTRIBUTE_NOT_SPECIFIED, //
+	MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECL, //
+	MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL, //
+	MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECL, //
 	MSG_SPACE_REQUIRED_AFTER_NOTATION_NAME_IN_NOTATIONDECL, //
 	NotationDeclUnterminated, //
 	OpenQuoteExpected, //
@@ -110,7 +114,7 @@ public static DTDErrorCode get(String name) {
 
 	/**
 	 * Create the LSP range from the SAX error.
-	 * 
+	 *
 	 * @param location
 	 * @param key
 	 * @param arguments
@@ -195,6 +199,13 @@ public static Range toLSPRange(XMLLocator location, DTDErrorCode code, Object[]
 		case MSG_ELEMENT_TYPE_REQUIRED_IN_ELEMENTDECL: {
 			return XMLPositionUtility.selectDTDDeclTagNameAt(offset, document);
 		}
+
+		case MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECL:
+		case MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL:
+		case MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECL: {
+			return XMLPositionUtility.selectDTDDeclTagNameAt(offset, document);
+		}
+
 		case dtd_not_found: {
 			// Check if DTD location comes from a xml-model/@href
 			String hrefLocation = (String) arguments[1];
@@ -220,5 +231,8 @@ public static void registerCodeActionParticipants(Map<String, ICodeActionPartici
 		if (sharedSettings.getWorkspaceSettings().isResourceOperationSupported(ResourceOperationKind.Create)) {
 			codeActions.put(dtd_not_found.getCode(), new dtd_not_foundCodeAction());
 		}
+		codeActions.put(MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECL.getCode(), new FixMissingSpaceCodeAction());
+		codeActions.put(MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL.getCode(), new FixMissingSpaceCodeAction());
+		codeActions.put(MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECL.getCode(), new FixMissingSpaceCodeAction());
 	}
 }
diff --git a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/codeactions/FixMissingSpaceCodeAction.java b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/codeactions/FixMissingSpaceCodeAction.java
new file mode 100644
index 0000000000..2a12fa3854
--- /dev/null
+++ b/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/codeactions/FixMissingSpaceCodeAction.java
@@ -0,0 +1,47 @@
+/*******************************************************************************
+* Copyright (c) 2020 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lemminx.extensions.contentmodel.participants.codeactions;
+
+import java.util.List;
+
+import org.eclipse.lemminx.commons.BadLocationException;
+import org.eclipse.lemminx.commons.CodeActionFactory;
+import org.eclipse.lemminx.dom.DOMDocument;
+import org.eclipse.lemminx.services.extensions.ICodeActionParticipant;
+import org.eclipse.lemminx.services.extensions.IComponentProvider;
+import org.eclipse.lemminx.settings.SharedSettings;
+import org.eclipse.lsp4j.CodeAction;
+import org.eclipse.lsp4j.Diagnostic;
+import org.eclipse.lsp4j.Range;
+
+/**
+ * Adds a space at the end of the diagnostic range
+ *
+ */
+public class FixMissingSpaceCodeAction implements ICodeActionParticipant {
+
+	@Override
+	public void doCodeAction(Diagnostic diagnostic, Range range, DOMDocument document, List<CodeAction> codeActions,
+			SharedSettings sharedSettings, IComponentProvider componentProvider) {
+		Range diagnosticRange = diagnostic.getRange();
+		try {
+			int startOffset = document.offsetAt(diagnosticRange.getStart());
+			int endOffset = document.offsetAt(diagnosticRange.getEnd());
+			String text = document.getText();
+			String value = text.substring(startOffset, endOffset);
+			codeActions.add(CodeActionFactory.insert("Add space after '" + value + "'", diagnosticRange.getEnd(), " ",
+					document.getTextDocument(), diagnostic));
+		} catch (BadLocationException | IndexOutOfBoundsException e) {
+			codeActions.add(CodeActionFactory.insert("Add space", diagnosticRange.getEnd(), " ",
+					document.getTextDocument(), diagnostic));
+		}
+	}
+
+}
diff --git a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/DTDDiagnosticsTest.java b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/DTDDiagnosticsTest.java
index a32ed2bbda..1cc1ea3efd 100644
--- a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/DTDDiagnosticsTest.java
+++ b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/DTDDiagnosticsTest.java
@@ -642,6 +642,73 @@ public void testDTDNotFoundWithPUBLIC() throws Exception {
 				d(5, 4, 5, 21, XMLSyntaxErrorCode.ETagRequired)); // [4]
 	}
 
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL_DTD() throws Exception {
+		String xml = "<!ELEMENTasdf (#PCDATA)>";
+		testDiagnosticsFor(xml, "test.dtd", d(0, 2, 9, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL_INLINE_DOCTYPE() throws Exception {
+		String xml = "<!DOCTYPE asdf [\n" + //
+				"  <!ELEMENTasdf (#PCDATA)>\n" + //
+				"]>";
+		testDiagnosticsFor(xml, d(1, 4, 11, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL_DTD_CLOSING_MISSING() throws Exception {
+		String xml = "<!ELEMENTasdf";
+		testDiagnosticsFor(xml, "test.dtd", d(0, 2, 9, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL_INLINE_DOCTYPE_CLOSING_MISSING() throws Exception {
+		String xml = "<!DOCTYPE asdf [\n" + //
+				"  <!ELEMENTasdf\n" + //
+				"]>";
+		testDiagnosticsFor(xml, d(1, 4, 11, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECL() throws Exception {
+		String xml = "<!ATTLISTasdf";
+		testDiagnosticsFor(xml, "test.dtd", d(0, 2, 9, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECL));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECL() throws Exception {
+		String xml = "<!ENTITYasdf";
+		testDiagnosticsFor(xml, "test.dtd", d(0, 2, 8, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECL));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECLCodeAction() throws Exception {
+		String xml = "<!DOCTYPE asdf [\n" + //
+				"  <!ELEMENTasdf\n" + //
+				"]>";
+		Diagnostic diagnostic = d(1, 4, 11, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ELEMENTDECL);
+		testCodeActionsFor(xml, diagnostic, ca(diagnostic, te(1, 11, 1, 11, " ")));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECLCodeAction() throws Exception {
+		String xml = "<!DOCTYPE asdf [\n" + //
+				"  <!ATTLISTasdf\n" + //
+				"]>";
+		Diagnostic diagnostic = d(1, 4, 11, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ELEMENT_TYPE_IN_ATTLISTDECL);
+		testCodeActionsFor(xml, diagnostic, ca(diagnostic, te(1, 11, 1, 11, " ")));
+	}
+
+	@Test
+	public void MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECLCodeAction() throws Exception {
+		String xml = "<!DOCTYPE asdf [\n" + //
+				"  <!ENTITYasdf\n" + //
+				"]>";
+				Diagnostic diagnostic = d(1, 4, 10, DTDErrorCode.MSG_SPACE_REQUIRED_BEFORE_ENTITY_NAME_IN_ENTITYDECL);
+		testCodeActionsFor(xml, diagnostic, ca(diagnostic, te(1, 10, 1, 10, " ")));
+	}
+
 	private static void testDiagnosticsFor(String xml, Diagnostic... expected) {
 		XMLAssert.testDiagnosticsFor(xml, "src/test/resources/catalogs/catalog.xml", expected);
 	}
@@ -649,4 +716,8 @@ private static void testDiagnosticsFor(String xml, Diagnostic... expected) {
 	private static void testPublicDiagnosticsFor(String xml, Diagnostic... expected) {
 		XMLAssert.testDiagnosticsFor(xml, "src/test/resources/catalogs/catalog-public.xml", expected);
 	}
+
+	private static void testDiagnosticsFor(String xml, String fileURI, Diagnostic... expected) {
+		XMLAssert.testDiagnosticsFor(xml, "src/test/resources/catalogs/catalog.xml", null, fileURI, expected);
+	}
 }