Hello when you go under the service catalog click on the catalog you want to maintain. Go under the settings section and you will see: Choose who can view this service item here you can select agent and requestor visibility based on groups. Hope this helps. 

Hello DaniS,

i know this, but the groups are only for internal. I need a selection for external customer. Customer A can see only service catalog A+B and other customer B can only see service Catalog C.

Internal and external is the same. They are all requesters in the system. 

Create dynamic requestergroups.

Very thanks, its running now.