The paper describes the work undertaken at the Institut de Cibernètica on the field of infrared (IR) sensor simulation. This work has led to the proposal of a simple IR sensor model as well as to the design and implementation of a simulation package allowing to emulate the behaviour of different IR sensors in a variety of working circumstances. The program permits independently defining the position and the beam patterns of both the IR emitter and receiver as well as dealing with different types of surfaces. The experimental results so far obtained confirm the validity of the simple model proposed for the IR sensor as well as the adequacy of the simulation approach introduced in the paper.