In this research, polyvinyl chloride based composite heterogeneous cation exchange membranes were prepared by the solution casting technique. Chitosan-co-iron nickel oxide nanoparticles were utilized as membrane surface modifier to improve the membranes electrochemical properties. The effect of additive nanoparticle concentration in the modifier solution on the properties of composite membranes was studied. SOM images showed uniform particle distribution and relatively uniform surfaces for the membranes. Results showed that transport number, selectivity and surface charge density were improved slightly by composite layer formation on the membrane surface. Results showed that ionic permeability and flux was initially decreased by the CS-co-Fe2NiO4 layer introducing a membrane surface and increased again by a further increase in the iron-nickel oxide nanoparticles ratio from 2 to 4 wt% in the modifier solution. The PVC/CS-co-Fe2NiO4 nanoparticles composite membranes showed higher electrical conductivity compared to the unmodified membrane. The results are valuable for elector-membrane processes especially in electrodialysis for water recovery and waste water treatment.