Two polycrystalline V 4 -cluster compounds of GaV 4 S 8 were prepared at different annealing temperatures (GaV 4 S 8 -1 sintered at 800 • C and GaV 4 S 8 -2 sintered at 500 • C). Their temperature-dependent resistivity and structural phase transformation temperature (45 K for GaV 4 S 8 -1 and 43 K for GaV 4 S 8 -2) are found to be very sensitive to the annealing condition. Above 320 K, activation energy ε 3 is calculated to be ∼0.23 eV which decreases to ∼0.18 eV around 300 K in GaV 4 S 8 -1 and GaV 4 S 8 -2 on cooling. According to percolation theory, the gradual decrease in ε 3 below 300 K is expected due to the increase in separation between V 4 -clusters are significantly different in GaV 4 S 8 -1 and GaV 4 S 8 -2. This statement is strongly supported by the calculated bandwidth per cluster in GaV 4 S 8 (∼0.342 eV in GaV 4 S 8 -1 and ∼0.374 eV in GaV 4 S 8 -2). A negative magnetoresistance (MR) is also found around 43 K in GaV 4 S 8 -2 at 6.0 T magnetic field associated with structural transition.