The influence of the reaction conditions and some aspects of the reaction network and changes in surface reactivity during the catalytic reaction in the selective oxidn. of 1-butene to 2-butanone (Me Et ketone, MEK) over supported Pd/V2O5 based catalysts at reaction temps. of around 120° are reported. In particular, the change in the selectivity to MEK as a function of time-onstream, the effect of a higher temp. treatment, the influence of the 1-butene, O2 and H2O concns. and the reaction temp., the nature of the support and the surface reactivity of MEK are shown. It is suggested that the catalytic behavior of Pd/V2O5 on alumina catalysts, characterized by the presence of a max. in the yield and selectivity to MEK, derives from the presence of a rate controlling effect of the desorption of MEK. [on SciFinder(R)]