The solubilities of lasalocid sodium in five organic solvents including methanol, ethanol, propan-2-ol, ethyl acetate and acetone were determined at temperatures ranging from 283.15 K to 323.15 K at atmospheric pressure using a gravimetric method and three novel polymorphic forms of lasaolocid sodium were observed. van't Hoff equation was used to correlate the experimental solubility data. The calculated values of van't Hoff equation were found to be in good agreement with the experimental data. Further, the dissolution enthalpy and entropy of lasalocid sodium in the corresponding solvents were calculated. (C) 2014 Elsevier B.V. All rights reserved.