We consider a single Dubins-like mobile robot traveling with a constant longitudinal speed in a planar region supporting an unknown field distribution. A single sensor provides the distribution value at the current robot location. We present a new sliding mode navigation strategy that drives the robot to the location where the field distribution attains its maximum. The proposed control algorithm does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous analysis and justification are provided. Simulation results confirm the applicability and performance of the proposed guidance approach. (C) 2010 Elsevier Ltd. All rights reserved.