A systematic survey of the catalytic effect of up to 10 wt% C60 carbon buckyballs on the kinetics of hydrogen desorption and subsequent absorption of magnesium hydride has been made. It was found that there was an optimum amount of C60 additive for the best desorption kinetics as well as an optimum time of ball-milling, improving the desorption kinetics over that of ball-milling alone. A comparison with the additive Nb2O5 under the same conditions indicated that desorption kinetic enhancement was relatively minor. The subsequent absorption kinetics were always poorer than the un-catalysed samples.