This paper presents a procedure for determining the optimal location and size of Static VAr Compensators (SVC) in a power system. Two objective functions have been considered for solving the optimization problem: a) minimize a Voltage Performance Index (VPI); b) minimize the total active power losses and the investment cost of the compensators (SVC). The performances of installing one or two SVC devices were analyzed. The simulations were performed on the IEEE 30-bus network using a software implemented in under Matlab by the authors.