In this paper, we study controllability and observability problems for the wave and heat equation in a spherical region in R n , where the control enters in the mixed boundary condition. In the main result, we show that all "finite energy" initial states (i.e. (wo,vo) x £ 2 (H)) can be steered to zero at time T, using a control / 6 L 2 (dO x [0, T]), provided T > 2. On this basis, we use the duality principle to investigate initial observability for the wave equation. Applying the Fourier transform technique, we obtain controllability and observability results for the heat equation.