In this paper we study the solution to optimal control problems for discrete time linear hybrid systems. First, we prove that the closed form of the state-feedback solution to finite time optimal control based on quadratic or linear norms performance criteria is a time-varying piecewise afine feedback control law. Then, we give an insight into the structure of the optimal state-feedback solution and of the value function. Finally, we briefly describe how the optimal control law can be computed by means of multiparametric programming.