The formulation of moxifloxacin was found liquid at the formulated pH and formed gel in the presence of mono or divalent cations. The gel formed in situ showed sustained drug release over a period of 10-12 h. The formulations were less viscous before instillation and formed strong gel after instilling it into cul-de-sac. It is thus concluded that by adopting a systematic formulation approach, an optimum point can be reached in the shortest time with minimum efforts to achieve desirable rheological and in vitro release property for in situ gel forming system.