The elastic constant matrix at room temperature and the temperature dependence of C-11 constant (30-400degreesC) of Na0.5Bi0.5TiO3 single crystal have been measured for the first time. The anomaly at the temperature, which corresponds to disappearing of ferroelectric state (similar to200degreesC), and broad minimum about temperature, which correlates to maximum of electric permittivity (similar to320degreesC), has been revealed. It has been concluded, that this minimum can be dynamic effect and does not indicate of the structural phase transition. Also the use of NBT for device applications has been indicated.