A joint research between Politecnico di Torino and COMAU is going on, aimed at defining a task oriented programming approach to allow soft skilled programmers to develop optimized programs for complex robotic cells. Within this paradigm, the user is simply asked to specify the features of the robotic cell and a structured set of tasks defining the required process. The paper is focused on the first step necessary to achieve the overall goal, i.e., the definition of a generic task model. The model is built starting from the analysis of the most important industrial applications, and can include physical and synchronization constraints, as well as various possible requirements and situations relative to the characteristics of the robots in the cell and of the involved work-pieces. A welding process is considered as typical industrial case study, to show how to build the corresponding task model according to the proposed approach.