This paper proposes an efficient chaotic differential harmony search (CDHS) algorithm to solve the dynamic economic and emission dispatch (DEED) problem with security constraints. The main objective of DEED problem is to determine the optimal power generation schedule for the online generating units over a time horizon at the same time satisfying the environmental and security constraints along with other generator constraints. The DEED problem is formulated as a nonlinear constrained multi-objective optimization problem. The fuel cost and emission are considered as two competing objectives. It is converted into a single objective function by introducing a price penalty factor. The price penalty factor blends the emission with the fuel cost. In the proposed algorithm, chaotic variables are introduced instead of random number generator in the differential mutation operator of differential harmony search (DHS) algorithm to accelerate the DHS algorithm to reach the global optimal solution quickly. The effectiveness of the proposed CDHS algorithm is demonstrated on IEEE-30 bus system with valve point effects, ramp rate limits, prohibited operating zones, and security constraints for a period of 24 hours. The simulation results obtained by the proposed CDHS algorithm are compared with DHS algorithm. The optimal solution obtained by the proposed algorithm is better than DHS algorithm in terms of solution quality, speed of convergence and computational time. © 2013 IEEE.