The surface properties (dispersive component gamma(S)(d) of surface energy and surface nanomorphology) of nickel oxide samples submitted to heat treatments up to 550 degrees C were examined by temperature programmed desorption (TPD) and inverse gas chromatography (IGC) methods. It is shown that the variation of gamma(S)(d) is complex, first increasing as the temperature reaches about 300 degrees C, then decreasing and going again through a maximum, of lower amplitude, for a treatment temperature of about 600 degrees C. These variations follow closely the TPD curves that relate the rate of H2O and, in a much lesser extend of CO2 releases as the heat treatment temperature augments. The surface nanomorphology changes also during this treatment. The NiO surface becomes very interactive when treated around 250 degrees C. The determination of the adsorption energy distribution curves (energetic heterogeneity) clearly demonstrates the change in surface properties and development of the population of high adsorption energy sites. Rehydration of the sample treated at 300 degrees C was not possible under our experimental conditions.