TheT0curve of the Si‐As system has been determined by pulsed laser melting of supersaturated solid solutions in the As concentration range between 0 and 12.5 at. %. Samples were irradiated with both 20‐ns 347‐nm‐wavelength and 20‐ps 532‐nm‐wavelength laser pulses, and surface melting has been revealed by time‐resolved reflectivity measurements. Melting temperatures of the solutions have been derived from the measurement of the energy absorbed at melting threshold. Some implications of our results on the thermodynamics of the Si‐As system are discussed.