Rate constants and products are reported for the decomposition of aryl N-(methoxycarbonyl)sulfamates 1a-h (range) in aqueous solutions (pH 0-14) at 50 degrees C. The pK(a) values at 25 degrees C of 1a-h are 0.46-2.40. The pH-rate profiles of 1 indicate a rate law that includes three terms : two pH independent terms, k(a) in acid and k(p) around neutral pH, with k(a) > k(p), and a hydroxide ion dependent term, k(OH). In acid, product analysis reveals that both S-O (k(SO2)) and C-O (k(CO)) bond cleavage reactions are involved. From an analysis of beta(1g), solvent isotope effects, and solvent isotopic labeling of the products, it is concluded (a) that the C-O cleavage reaction involves protonation of the leaving group methanol and its expulsion from the dipolar intermediate ArOSO2N-CO-O+HCH3 and (b) that the S-O cleavage reaction may involve either an intra- or an intermolecular general acid-catalyzed decomposition of 1 or 1-, respectively. in contrast to k(a), the spontaneous hydrolysis reaction of 1(-), k(p), takes place exclusively via S-O bond fission. The k(OH) reaction of 1(-) is rationalized by OH- attack either at the carbonyl center (1b-h) or at the aromatic ring (1a). It is concluded that the -SO2NHCO- group may be viewed as an attractive phosphate analogue.