In this paper, a sliding mode and adaptive observers are proposed for multicell converter. The aim is to solve the problem of capacitor's voltages estimation by tacking account the hybrid behavior appearing in the multicell converters. Furthermore, an analysis of convergence for both observers is introduced. Finally some illustrative results of a 3-cell-converter are given in order to show the efficiency of the designed observers. The applicability of the designed observers are emphasized by the robustness test with respect to resistance load variation.