Process of electrical contact heating can be described in spherical model of temperature distribution in electrical contacts introducing by R. Holm. In this research two phase spherical Stefan problem is considered and solution represented in series for integral error function and heat polynomials with undetermined coefficients. All coefficients are founded. Series convergence is proved by condition of constant temperature on the free boundary.

Keywords : Stefan Problem, Heat Polynomials, Integral Error Function, Free Boundaries, Faa-Di Bruno.