A new organic conductor, (BEST)(2)InBr4, with alternating donor layer arrangement has been synthesized, and the electrical properties have been investigated up to 10.8 GPa. The temperature dependence of the high-pressure resistivity shows a complicated metal-semiconductor transition behavior. The room temperature resistivity decreases with pressure up to 8.6 GPa but increases at higher pressures. The magnetic susceptibility of an isostructural (BEST)(2)FeBr4 salt shows an antiferromagnetic transition at 4.4 K, which is suppressed with increasing magnetic field.