Experimental and theoretical studies have been performed to demonstrate the high performance of the novel piezoelectric material GaAsO4. Hydrothermally grown single crystals of a-quartz phase GaAsO4 were studied by Brillouin spectroscopy to determine elastic constants. Experimentally obtained values of C-11, C-66, C-33, C-44, C-14 and C-12 are 59.32, 19.12, 103.54, 30.70, 1.7, and 21.1 GPa, respectively. Elastic and piezoelectric tensors were also calculated by a first principles method in this work, leading to a very good agreement with experimental results and confirming the values of elastic components obtained indirectly such as C-14 and the negligible piezoelectric correction for C-11. The thermal behavior of the elastic constant corresponding to the [100] longitudinal L mode (C-11) was studied up to 1137 K to estimate potential piezoelectric performance. It was found that the thermal behavior is linear up to 1273 K which is just below the thermal decomposition temperature of 1303 K. High thermal stability can be linked to the higher polarizability of large cations Ga and As because of neighboring oxygen atoms. On the basis of thermal behavior, GaAsO4 is a promising material for high temperature piezoelectric applications.