A method dedicated to the measurement of low surface tension coefficients in binary fluids is proposed. The method which is not intrusive and does not interfere with the volume/weight proportion of liquid composing the binary mixture utilizes excitation of progressive capillary waves by pulsed radiation pressure force of focused ultrasound beam. A known dispersion relationship for gravity-capillary waves is used to evaluate the surface tension coefficient. The experiments are carried out in microgravity conditions in order to make the capillary term of the relationship strongly dominant and thus to reduce artifacts in acquired data.