Abstract Receding as well as advancing water contact angles have been measured on glass surfaces treated with dichlorodimethysilane and with chlorotrimethysilane. The experimental data support the theory of contact-angle hysteresis on heterogeneous surfaces as proposed by Dettre and Johnson. Among the surfaces prepared here, the Me2SiCl2-treated one is unique in showing zero hysteresis, a result attributable to homogeneous coverage and structure. The Me3SiCl-treated surface appears to possess both micro- and macroheterogeneity. In these systems, the advancing angle is believed to approximate closely the equilibrium contact angle.