This paper presents a novel method of solving the economic dispatch (ED) problem with valve point effects using the intelligent water drop (IWD) algorithm. The IWD algorithm is a nature-inspired optimisation algorithm. A natural river chooses the best possible path from a lot of possible paths from source to destination. This idea is embedded in the proposed IWD based method for solving the ED problem. Global optimum can easily be achieved, at only a moderate computational effort. The proposed method has been applied to three test systems comprising 3, 13 and 40 units. These test systems are also solved using the catfish particle swarm optimisation (Catfish PSO) algorithm-an improved version of PSO-for the comparison and validation of the solutions. The results obtained by these two methods have been compared against existing results in the literature. Simulation results show that the proposed IWD method has good global search capability. © Research India Publications.