Nanosecond resolution time‐resolved x‐ray diffraction measurements have been used to study the temperature and temperature gradients in ⟨100⟩ and ⟨111⟩ oriented silicon crsytals during pulsed laser annealing. Thermal strain analysis of time‐resolved extended Bragg scattering has shown the lattice temperature to reach the melting point during 15‐ns, 1.5‐J/cm2ruby laser pulses and to remain at the melting point during the high reflectivity phase (HRP). The temperature gradients at the liquid‐solid interface were found to be in the range of ∼107K/cm during the HRP.