A modified Shepard interpolation method, developed for constructing potential energy surfaces (PESs) for gas phase reactions, has been adapted to generate PESs for molecule-surface reactions, and applied to the dissociative chemisorption of H-2 on Pt(111). To provide a test of the method, the input data were taken from an existing PES. Reaction probabilities computed using classical and quantum dynamics on the new PES are in excellent agreement with results for the old PES, the construction of which required twice as many points. This shows that the modified Shepard interpolation method can be used efficiently to build PESs which yield accurate dynamics results for molecule-surface reactions. (C) 2003 Elsevier B.V. All rights reserved.