Linear programming application for optimal active power flow under constraints shows very good results, without causing particular problems. However, the same technique is more difficult to apply to reactive power optimization, due to the nonlinearity of relations between the reactive power injections and the voltages. An iterative and decoupled method, based on optimization of injected reactive currents, for minimizing the production cost and active losses under bus voltage and branch flow constraints, is proposed. An illustrative example applied to an actual 220/125 kV network shows the possibilities, the efficiency and the limits of this method