Film permeability and double layer capacitance (C-dl) results are reported for mercaptotetradecanoic acid self-assembled monolayers (C13COOH SAMs) on gold substrates spanning a range of topography. Whereas film permeability was observed to decrease with increasing substrate smoothness, indicative of lower defect density in the SAMs, the capacitance, unexpectedly, was observed to increase as the topography became smoother. To explain these results, a simple structural model is proposed in which the extent of hydrogen bonding (H-bonding) among carboxylic acid endgroups is related to the underlying gold substrate topography. The model predicts that more extensive H-bonding will occur as substrates become smoother which, in turn, impacts the dielectric properties of the film. The model also provides an explanation for the discordant pK(a) results that have heretofore been reported for COOH SAMs. Altered surface acidity of up to 3 pK(a) units appears to be attributable to substrate topography.