This paper proposes the application of a Particle Swarm Optimization (PSO) algorithm to the Load Flow calculation in Power Systems. The proposed methodology is based on the minimization of power mismatches in the system buses. The power flow study provides the system status in the steady-state and it is fundamental to the power system operation, planning and control. PSO is applied in a new computational model for the system power flow obtainment. This model searches for a better convergence, as well as a wider application in comparison with traditional methods as the Newton-Raphson method. This methodology was tested with numerical experiments accomplished in an IEEE 6-Bus System.