This paper proposes a new method to solve the problem of economic dispatch (ED) withpiecewise quadratic cost function using particle swarm optimization (PSO). Traditionally, a single fuel cost function for each generator is used. However, some units use multiple fuels like coal, natural gas and oil, which have different heat contents. This multiple fuel option leads to piecewise quadratic cost function (PQCF) which is solved by traditional and non-traditional methods. The proposed approach using PSO is much simpler than these methods. The results obtained by using the PSO method are compared with the evolutionary programming (EP) in terms of solution quality and computational efficiency.