A simulated annealing like optimization method has been successfully applied for the determination of global minimum of equation of state (EoS) parameters. The approach is tested using the program TOPAS on a high precision variable pressure data set of quartz [R.J. Angel, D.R. Allan, R. Miletich, L.W. Finger: J. Appl. Cryst. Vol 30 (1997) p. 461] It is evidenced that least-squares refinement finds the global minimum for all EoS except for the Birch-Murnaghan EoS of fourth order for which it is shown that a clearly distinguished global minimum does not exist, at least for the used data set. The method presented herein serves as a fast test for the global minimum verification for the EoS parameters but should be applicable also to other optimisation problems.