Using the molecular-kinetic theory of wetting, we analyze the dynamic conta
ct angle of a sessile drop of squalane spreading spontaneously on Langmuir-
Blodgett multilayer substrates (behenic acid on glass). This allows the eff
ect of microscale roughness on the parameters appearing in the theory to be
determined. In particular, it is shown that the jump frequency of liquid m
olecules at the wetting line decreases with microroughness, supporting the
idea that surface defects induce additional pining potentials. The increase
in pinning potential can be explained in terms of a linear increase in the
activation free energy of wetting with increasing RMS microroughness.