To gain insight on the mechanistic aspects of the palladium-catalyzed hydrolysis of NaBH4 in alkaline media, the kinetics of the reaction has been investigated by B-11 NMR (nuclear magnetic resonance) measurements taken at different times during the reaction course. Working with BH4-concentration in the range 0.05-0.1 M and with a [substrate]/[catalyst] molar ratio of 0.03-0.11, hydrolysis has been found to follow a first-order kinetic dependence from concentration of both the substrate and the catalyst (Pd/C 10 wt%). We followed the reaction of NaBH4 and its perdeuterated analogue NaBD4 in H2O, in D2O and H2O/D2O mixtures. When the process was carried out in D2O, deuterium incorporation in BH4- afforded BH4-nDn-(n) 1, 2, 3, 4) species, and a competition between hydrolysis and hydrogen/deuterium exchange processes was observed. By fitting the kinetics NMR data by nonlinear least-squares regression techniques, the rate constants of the elementary steps involved in the palladium-catalyzed borohydride hydrolysis have been evaluated. Such a regression analysis was performed on a reaction scheme wherein the starting reactant BH4- is allowed both to reversibly exchange hydrogen with deuterium atoms of D2O and to irreversibly hydrolyze into borohydroxy species B(OD)(4)(-). In contrast to acid-catalyzed hydrolysis of sodium borohydride, our results indicate that in the palladium-catalyzed process the rate constants of the exchange processes are higher than those of the corresponding hydrolysis reactions.