diff --git a/src/main/java/org/xembly/AttrDirective.java b/src/main/java/org/xembly/AttrDirective.java
index db3d51f..0cb4103 100644
--- a/src/main/java/org/xembly/AttrDirective.java
+++ b/src/main/java/org/xembly/AttrDirective.java
@@ -75,8 +75,13 @@ public Directive.Cursor exec(final Node dom,
         final Directive.Cursor cursor, final Directive.Stack stack) {
         final String key = this.name.raw();
         final String val = this.value.raw();
+        final String[] parts = key.split(" ");
         for (final Node node : cursor) {
-            Element.class.cast(node).setAttribute(key, val);
+            if (parts.length == 2) {
+                Element.class.cast(node).setAttributeNS(parts[1], parts[0], val);
+            } else {
+                Element.class.cast(node).setAttribute(key, val);
+            }
         }
         return cursor;
     }
diff --git a/src/main/java/org/xembly/Directives.java b/src/main/java/org/xembly/Directives.java
index 4cae7dd..48374b9 100644
--- a/src/main/java/org/xembly/Directives.java
+++ b/src/main/java/org/xembly/Directives.java
@@ -332,6 +332,10 @@ public Directives remove() {
     /**
      * Set attribute.
      *
+     * <p>If it's necessary to add an attribute with a namespace, append
+     * the namespace to the name of the attribute, separating them
+     * with a space.</p>
+     *
      * <p>If a value provided contains illegal XML characters, a runtime
      * exception will be thrown. To avoid this, it is recommended to use
      * {@link Xembler#escape(String)}.
diff --git a/src/test/java/org/xembly/AttrDirectiveTest.java b/src/test/java/org/xembly/AttrDirectiveTest.java
index 0bc8036..f28ed89 100644
--- a/src/test/java/org/xembly/AttrDirectiveTest.java
+++ b/src/test/java/org/xembly/AttrDirectiveTest.java
@@ -30,10 +30,12 @@
 package org.xembly;
 
 import com.jcabi.matchers.XhtmlMatchers;
+import com.jcabi.xml.XMLDocument;
 import java.util.Collections;
 import javax.xml.parsers.DocumentBuilderFactory;
 import org.apache.commons.lang3.StringUtils;
 import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
@@ -100,4 +102,19 @@ void addsCaseSensitiveAttributesDirectly() throws Exception {
             XhtmlMatchers.hasXPath("/f[@Price='\u20ac50']")
         );
     }
+
+    @Test
+    void addAttributeWithNamespace() {
+        MatcherAssert.assertThat(
+            new XMLDocument(
+                new Xembler(
+                    new Directives().add("boom").attr(
+                        "noNamespaceSchemaLocation http://www.w3.org/2001/XMLSchema-instance",
+                        "foo.xsd"
+                    )
+                ).domQuietly()
+            ).nodes("/boom/@xsi:noNamespaceSchemaLocation"),
+            Matchers.not(Matchers.emptyIterable())
+        );
+    }
 }