We propose an evolutionary algorithm for the enhancement of digital semi-fragile watermaking based on the manipulation of the image discrete cosine transform (DCT). The algorithm searches for the optimal localization of the DCT of an image to place the mark image DCT coefficients. The problem is stated as a multi-objective optimization problem (MOP), that involves the simultaneous minimization of distortion and robustness criteria. Categories and Subject Descriptors 1 [Real World Applications]: Watermarking; 2 [Evolutive Strategies]: Multi-objective Optimization. General Terms Algorithms Keywords Genetic Algorithm, Multi-Objective, Watermarking.