The mesoscopic dynamics of the chemical Lorenz system has been examined within the framework of master equation description by means of ensemble stochastic simulations. The time evolution of the bin frequency, which approximates the probability of the master equation, has been checked in dynamic regimes of fixed points, limit cycles and chaos. The variances and covariances between different species are also calculated and compared. Results presented suggest a picture of mesoscopic dynamics beyond the usual deterministic description.