Nanocomposites of Ni/NiO, Ni/NiCo 2 O 4 and Co/Co 3 O 4 have been synthesized by a chemical reduction technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images confirm the mixed composite nature of the sample and uniform particle size of approximately 13nm. Formation of Ni/NiCo 3 O 4 solid solution or NiCo 2 O 4 spinel phase in the mixed composite is confirmed by energy dispersive X-ray (EDX) spectrum. Magnetic hysteresis (M–H) curves of the nanocomposites show excellent ferromagnetic (FM) nature at room temperature. Nonlinear optical transmission of the nanocomposites is measured using the open aperture Z-scan technique employing 7 nanosecond laser pulses at 532nm. Experimental results show that NiO/NiO–Co 3 O 4 /Co 3 O 4 nanocomposites exhibit good optical limiting performance. From the measurements and numerical fitting of the data to theory, it is found that nonlinear absorption has contributions from excited state absorption and two-photon absorption. Optical limiting is enhanced in Co 3 O 4 and Ni/NiCo 2 O 4 in which the Co 3 O 4 content has a larger volume ratio.