The capacitor placement in distribution systems has the objective of reduce the reactive currents at the feeders, as well as to reduce power losses and improve the voltage profiles in the distribution networks. This paper proposes to a new methodology to support the capacitor placement in radial distribution systems, based upon the application of a Sensitivity Matrix. This matrix evaluates the sensitivity of the voltage magnitudes at the network buses in relation to variations on the injections of reactive power. The approach was applied to actual distribution feeders with promising results, some of then described in the paper.