In this paper, the problem of applying H_infinity optimization synthesis to design a position controller for DC drives is considered. Robust stability, low sensitivity both to system parameter variations and exogenous disturbances, robust tracking property without steady-state error are expected to be achieved by means of H_infinty control theory. Firstly a simulation and then an experiment have been set up and tested by controlling the position of an unstable mechanical system represented by an inverted pendulum. The results obtained fully confirm the validity of the design procedure and the robustness of the proposed controller.