Polyurethane dispersions (PUD) are used as coating because of their high performance. Especially, due primarily to environmental reasons, PUD have grown commercially over the last twenty years. In this paper, the objective of this work is to evaluate some of the properties of dimethylol butanoic acid (DMBA) based PUD to compare with dimethylol propionic acid (DMPA) based PUD using to prepare widely waterborne PUD. The synthesis of PUD was carried out according to introduction of DMBA as a source of free acid. The results showed that DMBA was faster than DMPA in velocity of dissolvation and reaction time to form prepolymer, and lower in rising rate of viscosity.