diff --git a/lib/noosfero/api/entities.rb b/lib/noosfero/api/entities.rb
index 957f69d..640a055 100644
--- a/lib/noosfero/api/entities.rb
+++ b/lib/noosfero/api/entities.rb
@@ -62,6 +62,7 @@ module Noosfero
 
       class Category < CategoryBase
         root 'categories', 'category'
+        expose :id
         expose :slug
         expose :full_name do |category, options|
           category.full_name
--
libgit2 0.21.2