We applied the ultrasound treatment (UST) to improve properties of poly-Si thin films on glass substrates for thin-film transistor applications. A strong decrease of the sheet resistivity in hydrogenated films subjected to UST was observed. UST improves the film homogeneity as monitored by spatially resolved surface photovoltage mapping. Studies of hydrogenated thin-film transistors demonstrated remarkable UST induced improvement in transistor characteristics, especially, a reduction of leakage current by as much as one order of magnitude. All these effects are explained in terms of UST enhanced hydrogenation of poly-Si film.