The influence of UV radiation on the phase transformation of glycine to glycine was investigated at 25 degrees C in the absence and the presence of varying intensities of UV radiation. The transformation of the polymorph was monitored by continuously measuring the ultrasonic velocity in the crystallizer, and the crystals obtained were analyzed using XRD to determine the polymorphic form. In addition, the crystals were characterized by SEM, a particle sizer and ATR-FTIR. The results indicated that the UV radiation and its intensity have significant effects on the both the average particle size and the morphology of glycine crystals. To further understand the role of UV radiation and its intensity on glycine phase transformation, these experiments were also performed in the presence of propane-1,2,3-tricarboxylic acid. It was found that the presence of the additive in the crystallization media caused the transition time to be extended; however, the presence of both the additive and UV radiation lessened the phase transformation time significantly, depending on the increase in UV radiation intensity. In addition, TGA-MS results revealed that the amount of evolved gases in the presence of UV radiation was reduced, and that the UV radiation caused changes in the glycine.