The paper considers damping an uncontrollable electromagnetic torque ripple of a DC motor with permanent magnets in a stabilization system of a gyrostabilized platform by mixed H /H 2 ∞ control method. Experimental studies showed complexity of the changes in electromagnetic torque (a torque ripple) of motor due to changes of the rotor rotation angle and current consumption of power stabilization motor. This torque is sensed by the stabilization system as external perturbing moment and it is one of the causes of additional error in stabilization of a single-axis gyrostabilizer