The onset of oscillatory instability of Benard-Marangoni convection in a horizontal fluid layer, subject to the Coriolis force and internal heat generation, is investigated. The upper surface is deformably free and the lower surface is rigid. The characteristic equations of the perturbed state are solved numerically, using the Runge-Kutta-Gill’s shooting method and the Broyden’s method. The Crispation number C is significant for the occurrence of oscillatory modes. The results show that smaller absolute values of critical Marangoni number M(c) and frequency oi, take place at larger values of Crispation number C. The effect of the rotation is stabilizing, while that of the internal heat generation is strongly destabilizing. The Biot number B-i and the Bond number B-o increase the critical condition. For oscillatory modes, the Prandtl number Pr would decrease the stability.