diff --git a/app/serializers/rest/admin/domain_block_serializer.rb b/app/serializers/rest/admin/domain_block_serializer.rb
new file mode 100644
index 000000000..b955d008a
--- /dev/null
+++ b/app/serializers/rest/admin/domain_block_serializer.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class REST::Admin::DomainBlockSerializer < ActiveModel::Serializer
+  attributes :id, :domain, :created_at, :severity,
+             :reject_media, :reject_reports,
+             :private_comment, :public_comment, :obfuscate
+
+  def id
+    object.id.to_s
+  end
+end
diff --git a/app/serializers/rest/admin/existing_domain_block_error_serializer.rb b/app/serializers/rest/admin/existing_domain_block_error_serializer.rb
new file mode 100644
index 000000000..629566dad
--- /dev/null
+++ b/app/serializers/rest/admin/existing_domain_block_error_serializer.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class REST::Admin::ExistingDomainBlockErrorSerializer < ActiveModel::Serializer
+  attributes :error
+
+  has_one :existing_domain_block, serializer: REST::Admin::DomainBlockSerializer
+
+  def error
+    I18n.t('admin.domain_blocks.existing_domain_block', name: existing_domain_block.domain)
+  end
+
+  def existing_domain_block
+    object
+  end
+end