The difference in the melting temperature of unrelaxed and relaxed amorphous silicon has been determined by measuring the energy density threshold for surface melting during nanosecond laser irradiation (&lgr;=347 nm). The melting onset was detected by time‐resolved reflectivity technique. Using particular samples in which a surface unrelaxed layer was generated by reimplanting a 400‐nm‐thick relaxed amorphous Si (a‐Si) the difference in the melting temperature has been determined independently of the thermal properties of thea‐Si. The melting temperature of relaxeda‐Si resulted to be only 3.9% higher than that of unrelaxeda‐Si, while on the basis of calorimetric data an ∼14% difference was expected. The reasons for this discrepancy are discussed. In addition a 24% increase in the product of thermal conductivity and specific heat ofa‐Si upon relaxation has been found.