Comprehensive analytical procedures for the unequivocal determination of a newly encountered drug “ N -hydroxy-3,4-methylenedioxymethamphetamine (N-OH-MDMA)”, which is expected to be chemically unstable and thermally decomposed to MDMA during the analyses, have been investigated by using various qualitative analyses including color tests, thin layer chromatography (TLC), infrared spectroscopy (IR), gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS) and capillary electrophoresis/mass spectrometry (CE/MS). Stability of N-OH-MDMA in aqueous solutions with several pH values and its recovery throughout the liquid-liquid extraction with ethyl acetate (EA) were also examined. Both the color tests and TLC suggested that Simon's reagent and R f values were helpful for discrimination of N-OH-MDMA and MDMA. The IR spectra of both N-OH-MDMA hydrochloride and MDMA hydrochloride showed a sufficient difference, and the IR spectrum of N-OH-MDMA oxalate, could be identified by some of its specific peaks. GC/MS has demonstrated that both free base and its trifluoroacetyl derivative were easily decomposed to MDMA and other related products in the GC injection port, though trimethylsilyl derivatization prevented its pyrolytic disproportionation to MDMA. On the other hand, LC/MS, LC/MS/MS and CE/MS procedures were found to be reliable techniques for determination of N-OH-MDMA without its thermal and chemical decomposition. Based on the stability studies, N-OH-MDMA proved stable in acid solution, while it was expected to be transformed to isoquinoline-type compounds in neutral solution and readily decomposed to its relevant oxime in alkaline solution. Since no difference of the extraction efficiencies with EA was observed under the neutral and alkaline conditions, the extraction should be done under neutral condition to minimize its decomposition.