β-Hydroxyethylhydrazine (I) can be determined in crude mixtures from the reaction of N2H4.H2O and ethylene oxide, which also contains the by-products 1,1-bis(β-hydroxyethyl)hydrazine, 1,2-bis(β-hydroxyethyl)hydrazine, and β-(β-hydroxyethoxy)ethylhydrazine, by PMR in CDCl3.The I content can be determined from the integrated intensities of the CH2 proton bands, since I contains only 4 CH2 protons and each of the by-products contain 8 CH2 protons.I exhibits 2 triplets at 2.88 and 3.72 ppm, and the by-products spectra have 2 triplets at 2.68 and 3.73 ppm.