Stars are formed by gravitational collapse of dense cores in magnetized molecular clouds. Details of the earliest epochs of star formation process and protostellar evolution are only vaguely known and strongly depend on the accretion history. Thermodynamical modeling in terms of radiation transport and phase transitions is crucial to identify meaningful results. In this study, we use a gray treatment of radiative transfer coupled with hydrodynamics to simulate Larson's collapse. In spherically symmetric collapse simulations, we investigate properties of prestellar cores in the low mass regime.