In this research report, we study the inverse problem of identifying a Robin coefficient defined on some non accessible part of the boundary from measurements available on the other part of the boundary, for (u,p) solution of the Stokes system. We prove a Lipschitz stability estimate, under the a priori assumption that the Robin coefficient is piecewise constant. To do so, we use unique continuation estimates for the Stokes system proved in [BEG12] and the approach developed by E. Sincich in [Sin07] to solve a similar inverse problem for the Laplace equation