Parkinson's disease (PD) is a very serious neurological disorder, and current methods of treatment fail to achieve long-term control. SCH 420814 is a potent, selective, and orally active adenosine A2a receptor antagonist discovered by Schering-Plough. The stability testing provides evidence of the quality of a bulk drug when exposed to the influence of environmental factors. Moreover, the degradation profiles are critical to the safety and potency assessment of the drug candidate for clinical trials. The use of LC/MS(/MS) has a significant impact on degradation product characterization. In this study, a rapid, sensitive and method was developed for the determination of the degradation products of the stressed SCH 420814.