Abstract: To investigate the effect of solid surface characteristics on the mass transfer process of falling film absorption and other solarassisted applications,the lithium chloride-air absorption of on different vertical surfaces（stainless steel,PTFE plastic and each of these with super-hydrophilic modified surfaces）was experimentally studied. Results show that the smaller liquid contact angle on the solid surface was not only conducive to the expansion of liquid film and the reduction of film thickness,but also increased the frequency and amplitude of film surface waves. Thus,the liquid/air mass transfer could be promoted significantly. The liquid film thickness on stainless steel surface is 20% lower than that of the PTFE. The mass transfer rate is increased by 35% simultaneously. After the super-hydrophilic modification,the film thickness was further reduced by 15%. The amplitude/film thickness ratio was increased and the mass transfer rate was increased by 30% accordingly. The super-hydrophilic modification of plastic surfaces is more effective for improving the mass transfer performance. Though experiments,the empirical formulas that the falling film wavelength and amplitude vary with the contact angle on solid surface were obtained,and predicted the effects on the energy consumption and solar utilization rate of practical airconditioning systems. This study can help the engineering application in the fields of solar-assisted air conditioning,absorption refrigeration and evaporative cooling,etc.