The dependence of the firing conditions on the crystal structure formation of ZnGa2 O4 has been investigated. The effects of temperature and atmosphere were examined and gave evidence of the instability of the zinc gallate under a reducing atmosphere at temperatures above 600C. A new preparation route has allowed to synthesize ZnGa2 O4 at low-temperature, right from 300C, avoiding the decomposition of the matrix during the annealing.