The kinematics and dynamics of the Stewart platform, based on six pneumatic cylinders, are considered. Differential equations of motion and derived and the forces, providing the fulfillment of a given law of motion, are calculated. Inertia and weight of pneumatic cylinders are introduced into consideration. The obtained equations are used for the study of loaded Stewart platform, for which stability is achieved by feedback control. Numerical examples are provided. Refs 17. Figs 5. Tables 4.