We report measurements of third-order optical nonlinearity of the 90GeS(2)-5Ga(2)S(3)-5CdS (in mol%) chalcogenide glass using the femtosecond time-resolved optical Kerr gate technique at 820 nm. The third-order nonlinear susceptibility was estimated to be as large as 1.0 x 10(-12) esu. The full width at half maximum of the Kerr signal was 150 fs, implying that the sample had a response faster than 120 fs. Its response was dominantly assigned to the ultrafast distortion of the electron cloud. This glass sample is promising in future all-optical switching devices. (C) 2004 Elsevier B.V. All rights reserved.