The glass-crystalline transformation induced by laser irradiation is studied in MoO3. Before crystallization we have found that the system evolves from a low temperature glass phase to a high temperature glass phase. The crystallization kinetics depend strongly on the initial irradiation power. The power densities needed to induce the phase transformations, of the order of 15 W/mm2, are relatively low and suggest the possibility of using this material as a data storage medium.