The solubility of berberine chloride in ethanol, 2-propanol, 1-butanol, 1-octanol, ethanol + 2-propanol, ethanol + 1-butanol, and ethanol + 1-octanol was measured. According to the molecular structure of berberine chloride, we defined a new group [C5H2N+] based on the existing parameter table of UNIFAC (Dortmund) and derived the group parameters. The experimental solubility data were well correlated by the UNIFAC model. These newly defined groups and parameters could be expected to allow the prediction of the solubility of other isoquinoline alkaloids.