The aim of the study was evaluation the thermorheological properties of myofibrillar proteins, determination of initial and final temperature of gelation process during meat ageing sonicated right after the slaughter with low frequency ultrasonic. The tests were carried out on semimembranosus muscles of young bulls. The sample was divided on three parts right after slaughter, first as a control sample and other two designated to ultrasonic treatment with 25 kHz (U) i 45 kHz (Z) frequency. The viscosity tests on homogenates from meat after 24, 48 and 72 hours of ageing in cooling conditions were evaluated. The acidity level was set up on pH 5.3 and 7.0 respectively. The initiative and final gelation temperature was set up. The tests showed that the changes of homogenates features prepared from meat in 0.6 M NaCl solution depend on the way of sonication, time after slaughter and acidity level. It was stated that setting up an acidity on 5.3 level leads to proteins coagulation. In the neutral acidity thermorheological changes of the muscle homogenates of all tested samples started around 60ºC. Sonicated samples (pH 7,0) characterized 1-2ºC higher initial temperature of viscosity changes in comparison to control sample.