Experimental results on the solubility c of ammonium oxalate in mixed water-acetone solvents containing acetone content x < 0.55 by weight at different saturation temperature T are presented and discussed using the theory of regular solutions. It was found that: (1) the dependence of the solubility c of ammonium oxalate in solutions of different mixed water-acetone solvents on temperature T follows an Arrhenius-type relation, (2) the dependence of c on acetone content x at different temperature T follows the relation: ln(c + delta) = a - bx, where the parameters a and b are measures of deviation of a solution from ideality and the correction factor delta is related to the activity coefficient f(a) of the solution, which decreases with an increase in c, and (3) the dependence of the solubility c of ammonium oxalate in solutions of different compositions x of water-acetone mixtures is related to the dielectric constant epsilon*. of the solvent mixture, following the relation ln c = C + C-1 epsilon*, where C and C-1 are related to the parameters a and b, respectively. Study of the metastable zone width, defined as maximum undercooling Delta T-max a solution saturated at a particular temperature T can withstand, of some selected solutions of mixed water-acetone solvents at different T revealed that Delta T-max decreases with an increase in antisolvent content x. The results are discussed using the self-consistent Nkylt-like approach. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.