dThe new hydrides CeNiSnH1.0(2) and CeNiSnH1.8(2) have been investigated by X-ray powder diffraction, magnetization, electrical resistivity and specific heat measurements. The hydrogen insertion into CeNiSn reveals an interesting magnetic transition: Kondo insulator (CeNiSn)--> antiferromagnet (CeNiSnH1.0(2)) ferromagnet (CeNiSnH1.8(2)). The physical properties of these compounds are influenced by the Kondo effect. (C) 2003 Elsevier B.V. All rights reserved.