 From the early 1970s he was active in the Union of Municipal Employees (GDG), of which he was chairman from May 2003 on.From 1990 he was a member of the Vienna City Council and the State Parliament, from 1995 also chairman of the local council.After Hundstorfer had been elected President of the ÖGB, he resigned from the Vienna legislature and municipal council on 25 January 2007.