The x-ray diffraction measurements of 2-propanol adsorbed on graphite have been taken over the temperature range 150-240 K and the coverage range 2.28-4.23 molecules/nm(2). The analysis of the data by means of the least-squares fitting of the complete pattern suggests that 2-propanol dimers bound by hydrogen bonding are arranged to give a lamellar structure of the molecules on the surface. The melting of the solid monolayers occurs by a two-step process involving an intermediate phase, possibly a defective two-dimensional smectic liquid crystal. The results are compared with the melting behavior observed for the monolayers of n-propanol.