The solubility of N-guanylurea dinitramide (GUDN, Fox-12) in binary solvent mixtures was measured. Binary solvents such as dimethyl sulfoxide (DMSO)/water and N,N-dimethylacetamide (DMA)/water were investigated. The temperature was in the range of 0 degrees C to 70 degrees C for DMA-water and 20 degrees C to 70 degrees C for DMSO-water. The temperature dependence on the solubility was higher in DMA-water than in DMSO-water at the same fraction of water. On the other hand, the modeling data was obtained by using the Apelblat equation. The average relative errors are less than 3%. Supersaturation for crystallization of GUDN in solution can be easily generated by adding water in DMSO (or DMA).