Abstract Syndiotactic polymerization of styrene in aliphatic solvents (hexane and cyclohexane) and aliphatic solvent/toluene mixtures was evaluated using a previously reported catalytic system formed by FluTi(O i Pr) 3 /MAO in order to evaluate polymerization reaction conditions and their effect on polymer tacticity. Highly syndiotactic polystyrene was produced indistinctly using pure aliphatic solvent or mixtures with toluene. On the other hand, the effect of polymerization conditions such as temperature, catalyst precursor and styrene concentrations, Al/Ti ratio and aliphatic solvent/toluene ratio over catalytic activity were analyzed.