In this contribution, we focus on a recently presented controller design method, called modied optimal control. This approach yields a closed form solution of a modied optimal control problem and achieves global asymptotic stability and suitable closed loop system dynamics. Since this method uses a control Lyapunov function, we present a new practically applicable procedure to construct this special kind of function. In order to demonstrate the eciency and the advantages of our method, a nonlinear controller is designed for a rotating rigid spacecraft. 1 Introduction Unmanned spacecraft have the potential of considerably reducing the cost and risk involved in the commercial and scientic exploitation of space since they represent a safe and economical complement or alternative to man in construction, maintenance, and operation of space structures. Accurate and eective control of spacecraft is a signicant challenge due to the inherent nonlinearity of their dynamics; see [11, 17] an...