The pyroelectric coefficient distribution that represents the polarization profile of pure SBN and SBN crystals doped with europium and rhodium was determined from the pyroelectric response by analyzing the time dependence of the pyroelectric response by using the thermal square wave method at single frequency. It has been shown that the dependence of the domain distribution density along the polar axis obtained from the domain images is in accordance with pyroelectric coefficient distribution over the thickness of investigated crystals.