In this study, NiFe2O4 powder samples of different crystallite sizes were prepared and characterised by powder x-ray diffraction, attenuated total reflection infrared spectroscopy, near ambient pressure x-ray photoelectron spectroscopy, nitrogen physisorption and temperature programmed reduction and desorption experiments. Their catalytic activities in the gas phase oxidative dehydrogenation of 2-propanol at different 2-propanol:oxygen ratios and reactions possibly taking place both parallelly and consecutively were tested and the species occurring in oxidative dehydrogenation settings investigated by operando infrared spectroscopy experiments and the influence of the crystallite size on the activity discussed.