Using a melting-resolidification process, mixed crystals of 1:1 molar ratio were prepared by the combination of various methyl-substituted nitroanilines 7-14 and unsubstituted nitroanilines 1-3 and nitrophenols 4-6. The mixed crystals were characterized by powder X-ray diffractometry (PXD), IR spectroscopy and differential scanning calorimetry. Among seventy six mixed crystals prepared, twenty one mixed crystals showed new PXD and IR peaks which are different from those of the components, suggesting the formation of a molecular compound. The second harmonic generation (SHG) activities were measured.