High molecular weight polyethersulfone (PES) nanoporous membranes modified with different loading of calcium chloride (0.5, 1, 2 and 3 wt.%) were prepared by dry-wet phase inversion method. Low molecular weight polyethylene glycol (PEG200) was used as pore constrictor and pore former for the blend membrane series. Fabricated membranes were characterized with various analytical and experimental techniques. Results showed that the CaCl2 blend PES/PEG200 membranes were nanoporous in nature with improved porosity and permeability. Addition of CaCl2 improved the mechanical stability and water permeability of the composite membranes. Performance of CaCl2 incorporated PES/PEG 200 membranes was investigated using selected dyes (congo red, orange II, crystal violet and methylene blue) and salts (Na2SO4 and MgSO4) separation from its aqueous solution. CaCl2 doped membrane showed better dye rejection behaviour with a permeate flux sequence as congo red < crystal violet < orange II < methylene blue. Size and charge based exclusions along with adsorption were identified as the separating principles. Fouling analysis clearly showed that CaCl2 incorporated membranes possessed better antifouling effect than membrane without CaCl2. Studies indicated that 1 wt.% CaCl2 loaded PES/PEG 200 membrane showed better performance than other fabricated CaCl2 blend membranes. Thus the CaCl2 blended PES/PEG200 membranes are promising for the treatment of dye polluted wastewater. © 2019 Institution of Chemical Engineers