diff --git a/java/code/src/com/redhat/rhn/frontend/xmlrpc/serializer/ContentEnvironmentSerializer.java b/java/code/src/com/redhat/rhn/frontend/xmlrpc/serializer/ContentEnvironmentSerializer.java
index 704e170b63df..72186b23723d 100644
--- a/java/code/src/com/redhat/rhn/frontend/xmlrpc/serializer/ContentEnvironmentSerializer.java
+++ b/java/code/src/com/redhat/rhn/frontend/xmlrpc/serializer/ContentEnvironmentSerializer.java
@@ -33,6 +33,7 @@
  *   #prop("string", "description")
  *   #prop("int", "version")
  *   #prop("string", "status")
+ *   #prop_desc("$date", "lastBuildDate", "last build/promote date")
  *   #prop("string", "contentProjectLabel")
  *   #prop("string", "previousEnvironmentLabel")
  *   #prop("string", "nextEnvironmentLabel")
@@ -54,6 +55,7 @@ public SerializedApiResponse serialize(ContentEnvironment src) {
                 .add("description", src.getDescription())
                 .add("version", src.getVersion())
                 .add("status", src.computeStatus().map(EnvironmentTarget.Status::getLabel).orElse("unknown"))
+                .add("lastBuildDate", src.computeBuiltTime().orElse(null))
                 .add("contentProjectLabel", src.getContentProject().getLabel())
                 .add("previousEnvironmentLabel", src.getPrevEnvironmentOpt()
                         .map(ContentEnvironment::getLabel).orElse(null))
diff --git a/java/spacewalk-java.changes.cbbayburt.clm-promote-date b/java/spacewalk-java.changes.cbbayburt.clm-promote-date
new file mode 100644
index 000000000000..fc20c368d538
--- /dev/null
+++ b/java/spacewalk-java.changes.cbbayburt.clm-promote-date
@@ -0,0 +1 @@
+- Add environment build/promote date to CLM API output (jsc#SUMA-280)