Within the scope of investigations carried out to find a new reactant for dissolution off-gas scrubbing in spent fuel reprocessing, this paper reports the study of the reaction between hydroxylamine and methyl iodide in an aqueous solution. The products with an excess of hydroxylamine were ascribed to be iodide and N-methylhydroxylamine. The main contribution of this work was the kinetics investigations from 25 to 55 degreesC within a pH range of 2.2-13.6 (analytical data obtained by ion chromatography), operating conditions for which no sufficient data were available from the literature. NH3OH+ was found to be nonreactive. The NH2OH/CH3I and NH2O-/CH3I reactions, the second one having not been investigated so far, were first order with respect to each reactant, with second-order rate constants of respectively (4.30 +/- 0.25) x 10(-3) and (2.05 +/- 0.25) x 10(-1) mol(-1) L s(-1) at 55 degreesC and activation energies of 98.3 +/- 3.4 and 67.4 +/- 2.9 kJ mol(-1). These results are consistent with estimations from a Bronsted correlation established for nitrogen nucleophiles. Edwards and Swain-Scott nucleophilic constants, not reported in the literature up to now, were calculated in water at 25 degreesC and compared to hydrazine and inorganic anions of potential interest within the scope of spent fuel reprocessing. An Ampac computational study of the transition state of the NH2OH/CH3I reaction was performed in gaseous media.