In this work, the solubility of 1,3-dimethylurea form I (DMUI) in seven solvents including water, 2-butanol, 2-propanol, acetone, acetonitrile, ethyl acetate and butyl acetate were measured by a synthetic method at a temperature range from (288.15 to 328.15) K at atmospheric pressure. For the temperature range investigated, the solubility of DMUI in the selected solvents increased with increasing temperature. Results of these measurements were well-correlated with the modified Apelblat equation, lambda h equation, van't Hoff equation and Wilson model. Besides, the thermodynamic data (i.e., Gibbs energy, enthalpy, and entropy of mixing) were calculated by using the Wilson model. The chemical potential, solvation free energy and interaction enthalpy of DMU in solution were calculated by COSMO-RS model. This model was also applied to predict DMU solubility which showed good agreement with the experimental values. (C) 2016 Elsevier Ltd. All rights reserved.