This paper presents a new approach for integral sliding mode controller for a class of unmatched uncertain systems. A nominal control is computed using sliding mode techniques which works for unmatched uncertain system. Integral sliding mode is further added to ensure robust reaching phase. A control system for slosh-free motion of a partially filled liquid container is sought. This is representative of a broader class of systems to which the proposed methodology is applicable. A simple pendulum model is considered to represent a fundamental mode of the lateral slosh. The effectiveness of the proposed scheme is demonstrated by simulation results. © 2010 IEEE.