Laser photolysis of NO2 has been combined with laser-induced fluorescence detection of the nascent OH product to investigate the dynamics of the reactions of O(P-3) with a series of saturated hydrocarbons. We confirm previous observations of very low fractions of OH rotational energy release for the higher homologues such as isobutane and cyclohexane. By photolysing NO2 at shorter wavelengths to produce translationally hotter O(P-3) atoms, we have been able to extend the measurements to the previously unstudied parent members of the series, methane and ethane. Similar low levels of rotational energy release were found, suggesting that the previously proposed strong collinear constraint also applies to CH4 and C2H6. No preference for either OH Lambda-doublet component was observed, also consistent with a collinearly constrained reaction. The OH spin-orbit states were found to be nonstatistically populated. In part II we present a detailed discussion of the potential source of the spin-orbit propensities.