The solubility of N-(4-chlorophenyl)-2-(pyridin-4-ylcarbonyl) hydrazinecarbothioamide (isoniazid analogue) in mono-solvents (water and polyethylene glycol 400 (PEG 400)) and various PEG 400 + water co-solvent mixtures was measured from (298.15 to 338.15)K using the shake flask method. The experimental solubilities were correlated with Apelblat equation and log-linear model of Yalkowsky. The root mean square deviations were observed in the range of 0.007-0.052 for Apelblat equation. However, the mean absolute errors were observed in the range of (036-4.94)% for log-linear model of Yalkowslcy. Experimental solubilities of isoniazid analogue were correlated well with Apelblat equation and Yalkowsky model. The solubility of isoniazid analogue was observed highest and lowest in pure PEG 400 (0.108 at 298.15 K) and pure water (5.17 x 10(-7) at 298.15 K), respectively. Based on solubility results, isoniazid analogue has been considered as freely soluble in PEG 400 and practically insoluble in water. The solubility data of this study could be useful in formulation development of isoniazid analogue in pharmaceutical industries. (C) 2014 Elsevier B.V. All rights reserved.