In the present study, mixtures of gemini surfactant (T3H1S2H1T3) and a conventional surfactant (A(4)B(4)) in aqueous solutions have been investigated through coarse-grained Monte Carlo simulation. The Critical Micelle Concentration (CMC) and aggregation numbers have been calculated at different ratios of the T3H1S2H1T3/A(4)B(4) surfactant mixture. The mixed CMC of the binary combinations falls between those of constituent surfactants. To explain the simulation results, theoretical models like Clint, Rubingh, and Maeda have been used to evaluate the interaction parameter, micellar composition, activity coefficients and the free energies of micellization. By increasing the overall composition until it reaches 0.5, all these parameters indicate non-ideal behavior and synergistic interactions between the surfactants, which is explained in terms of reduction of repulsion between head groups of T3H1S2H1T3 due to the presence of conventional surfactants. At higher ratios, the formation of the aggregations would be harder due to the higher concentration of A(4)B(4). (C) 2015 Elsevier B.V. All rights reserved.