In this work, ultrafiltration (UF) mixed matrix membranes (MMMs) incorporated with hydrophilic hydrous manganese oxide (HMO) nanoparticles were synthesized and used for the treatment process of a highly concentrated oily solution. The MMMs were fabricated via a phase inversion process and were characterized with respect to physiochemical properties and filtration performances. The results showed that the MMMs demonstrated higher water flux and better oil rejection rates compared to the control membrane (without HMO incorporation) when tested at three different oily solutions with oil concentration in the range of 5000-15000ppm. The membrane incorporated with the highest amount of HMO (labelled as MMM-2) in particular showed the best results even when subjected to 15000ppm oily solution filtration, recording water flux of 32.2 L/m(2)hbar and oil rejection of 82%. The enhanced performance can be attributed to improved surface hydrophilicity coupled with better structural integrity and higher porosity that contributed to lower degree of oil molecules deposition and greater water transport rate. It was also reported that with the use of a feed spacer during the filtration process, the degree of flux deterioration of MMMs could be further reduced without compromising rejection. The findings of this work indicated the potential of MMMs for the treatment of highly concentrated oily effluent produced from industries, by producing permeate of high quality at reasonably good water permeability.