The solubility of two forms of imidacloprid, forms I and II, in seven pure organic solvents was measured using the analytical gravimetric method. It was shown that the solubility of the two forms of imidacloprid increases as the temperature increases. Meanwhile, the solubility at a low temperature follows the order methyl acetate > ethyl acetate > n-butyl acetate > methanol > ethanol > n-propanol > n-butanol and the order at relatively high temperatures is methyl acetate > ethyl acetate > methanol > n-butyl acetate > ethanol > n-propanol > n-butanol. Differential scanning calorimetry and solubility data show that the two forms are monotropically related and form I is the stable phase. Besides, the experimental solubility of forms I and II in the seven pure solvents is well correlated by the modified Apelblat model and lambda h model, respectively.