This study fundamentally investigated the swelling and distribution of benzene-light nonaqueous phase liquid (LNAPL) in porous media while cosolvent was flushed to the benzene-partially saturated system. Furthermore, the effects of simultaneous injection of cosolvent and air on the LNAPL behavior were visualized and thus quantified within a two-dimensional transparent porous medium. Partitioning types of alcohols affected dissolution of benzene entrapped in porous media. Tert-butanol (TBA) and 1-propanol floods apparently increased the LNAPL area, while a 70% ethanol flood reduced the LNAPL area by dissolution. Airflow facilitates mobilization of the swollen LNAPL by TBA and 1-propanol. while it facilitates dissolution of non-swollen LNAPL by ethanol. Therefore, LNAPL behavior during cosolvent flooding would be determined by partitioning type of alcohols and the presence of airflow. (C) 2008 Elsevier B.V. All rights reserved.