The aim of this study is to determine the temperature profile at the inlet of an extrusion die by measurements in unsteady flow. Temperature measurements are collected by thermocouples installed along the die, in walls, at the borders of the extrusion channel. Measured temperatures are function of the inlet temperature profile, which we are looking for, of the heat generated by the viscous dissipation and of thermal transfers inside the walls and inside the extrudated polymer. Sensitivity to all those phenomena is thus a crucial problem. Our model describes flow, heat generation, thermal exchanges, and their coupling by thermal rheological laws. Experimental validation of numerical results is provided thanks to real measurements from an instrumented die. The adjoint method is used to solve the inverse problem. First results are shown and analyzed. (c) 2007 Elsevier B.V. All rights reserved.