This study investigated the chitosan-mediated (C-M) synthesis of C-M NiO (using banana peel ash as green alkali source), its composition and application as catalyst in the hydrogenation of soybean oil. C-M NiO was synthesized from the reaction of equal volumes (10 ml) of 0.01 M NiSO4.7H2O, ash filtrate and chitosan solution (0.1 g of chitosan in 100 ml of distilled water); while the control (NiO) was done without chitosan solution. Both catalysts were applied separately in the hydrogenation of soybean oil (n-hexane extract of dry soybean seed) under optimal condition with hydrogen gas and the products characterized with gas chromatography-mass spectrometric method (GC-MS). Characterization of the catalysts with X-ray diffraction (XRD) revealed mixed phase materials (majorly KCl/NiO, NiO and Ni(OH)2) with broader peaks for the C-M NiO, while EDXRF confirmed the presence of K, Ni and Rb with higher intensities than those of C (graphite), Zn, Mg, Fe, Br and Cl. Also, AAS was used to quantify Ni and K (major elements from EDXRF). The results gave mean [Ni2+] and [K+] as 11.87 ± 0.32 and 90.35 ± 0.03 mgL-1for C-M NiO but relatively higher concentrations of 14.86 ± 0.63 and 99.73 ± 0.06 mgL-1 respectively were obtained for NiO. SEM showed wider porous or multichannel skeletal polycrystallite networks for C-M NiO than NiO. GC-MS results indicated huge reduction in linoleic acid (dominant unsaturated fatty acid) from 55.12% to 7.54% for NiO and from 55.12% to 0% for the C-M NiO respectively, while stearic acid (saturated) increased from 4.55% to 46.18% for the control and 4.53% to 65.48% for the C-M NiO due to enhanced selectivity and catalytic conversion of unsaturated bonds to single bonds by the catalysts. Compositionally, the catalysts were confirmed to be K-major and were tagged KCl/NiO (K-rich) and C-M KCl/NiO (K-rich) respectively.