A recently proposed isotherm model for adsorption on fractal surfaces is fitted to a wide range of isotherm data obtained from the literature. All curve fitting attempts produced good fits and the model parameters obtained are shown to be physically reasonable. Also, all significant model parametrs can be obtained from a single isotherm. As expected, when surface roughness is taken into account, the specific surface area determined from monolayer volume may be significantly higher than that obtained using the standard smooth surface isotherm models.