Abstract Using steady state and time resolved fluorescence techniques, the photophysical parameters of acridone in w/o microemulsions of aerosol OT/isooctane were obtained. The results point to the existence of two species of acridone in equilibrium. In this equilibrium some water molecules are involved. The acridone species were localized at the micellar interface and in the water pool, respectively. The pseudo-equilibrium constant of the displacement process and the number of water molecules needed to displace acridone from the organic interface to the water pool were determined. In the presence of two different molecular weight polyvinyl pyrrolidone polymers the two species of acridone were also detected. The pseudo-equilibrium constant and the water molecules involved in the distribution equilibrium have also been determined and were compared with those obtained in nonperturbed microemulsions. Their differences are related with the average droplet occupancy and with changes on the water pool polarity induced by the addition of water soluble polymers.