Combined heat and power (CHP) plant generates electrical power as well as heat energy in a single process yielding more than 80% overall efficiency and reduces emission level significantly. The production of power and heat in CHP unit is mutually dependent on each other and is constrained by the feasible operating region. This paper presents a maiden formulation as well as a method for solution of the dynamic optimal load flow problem in power system involving CHP. A bio-inspired Krill Herd Algorithm has been utilized for minimization of cost of production, while maintaining voltage level at all buses and satisfying all other constraints. Herding behavior of Krill individuals is the basis on which this algorithm works. The distance of each Krill individual from food and the highest density of swarm are considered as the fitness function. Two test systems, one with 6 generators and the other with 19 generators have been considered to verify the effectiveness of this algorithm. Both the systems include a number of CHP units and have been adapted from IEEE standard Test Systems. The test results are encouraging. (C) 2017 Elsevier Ltd. All rights reserved.