Context: The field of IT processes lacks a scientifically-based tool that constructs organisation-specific IT processes according to the organisation's socio-technical characteristics. Objective: In this paper we propose a solution to this problem in the form of IT process engineering (ITPE). ITPE is based on established method engineering principles which we have adapted to IT process construction. Method: The tool was demonstrated by having three organisations use ITPE to each construct two IT processes. Results: ITPE provided useful guidance in all three cases. Conclusions: The study demonstrates that method engineering principles can be applied in research fields other than information system development.