Pure tetravalent nickel in gamma-type cobalt substituted nickel oxyhydroxide, Ni0.70Co0.30O2K0.30(H2O)(0.42), could be obtained by the "chimie douce" reaction. The presence of tetravalent nickel is confirmed by comparing the Ni It-edge XANES spectrum of the sample with those of reference compounds having various nickel valency and similar layer structure. The Co K-edge XANES spectrum indicates that the trivalent cobalt remains unchanged regardless of the nickel valency. The structural modification during chimie douce reaction observed from XRD patterns and the result of iodometric titration are consistent with the Ni and Co It-edge XANES data.