Oswald Kleiner advises and represents companies and entrepreneurs in and out of court in matters of business law. His main areas of focus include the establishment and reorganization of companies, the sale of companies and - as the case may be - its shares; in particular arrangements for company succession. Close cooperation with the client’s respective tax advisor or/and financial auditor is an absolute requirement for his work. An additional emphasis of his work is real estate law. Here Oswald Kleiner advises on real estate transactions of various sizes. On the subject of banking law he continuously represents several financial institutions in and out of court.
In matters of public procurement law he advises mainly public institutions with respect to the development, implementation and judicial review of formal award and structured tender procedures, such as in the areas of infrastructure or extensive building works and within the framework of public private partnerships.

Oswald Kleiner is a member of the executive board of several trusts.