[en] For pt.II see ibid., vol.3, p.159-64, 1998. Double-differential cross sections (energy spectra) for proton and deuteron emission in fast neutron induced reactions on oxygen are reported for nine incident neutron energies between 25 and 65 MeV. Angular distributions were measured at 15 laboratory angles between 20 and 160 . Procedures for data taking and data reduction are presented. Deduced energy-differential, angle-differential and total cross sections are also reported. Experimental cross sections are compared with existing data and with theoretical model calculations. (orig.)