Biofouling is an on-going challenge in reverse osmosis (RO) systems, and the feed spacer within the RO membranes showed to have an essential role in biofouling. In this study, 3 anti-biofouling materials: propolis, chitosan-propolis mixture, and Poly 3-Sulfopropyl methacrylate potassium salt (PolySPMA) were coated on polypropylene (PP) surface and tested for surface characteristics. Then a suitable material for the feed spacer coating was chosen based on the results. Then the effect of coated feed spacer was tested in a pilot scale RO system. Although propolis and chitosan-propolis coatings showed hydrophilic, and microscopically smooth surfaces with least amount of leaching, it was not recommended as an antibiofouling material. PolySPMA resulted in very hydrophilic, yet microscopically rough surface with almost half of the grafted constituents lost after leaching test. Reinforcements were made where PolySPMA of high concentration monomer solution and pre-heated temperature with long feed spacer incubation time was chosen for pilot plant experiment. The coated and the uncoated feed spacer containing RO test cells showed significant differences. Feed channel pressure drop (FCP) increase was almost 3 times less for the coated than the uncoated. The effect of biofouling on FCP was delayed for 2 days for the coated feed spacer containing test cell. From the biofilm analysis, fewer amounts of organic carbon and cells were present on the coated feed spacer compared to the uncoated. The improved anti-biofouling is most probably responsible due to the strong hydrophilic nature and presence of negative charge on PolySPMA grafted feed spacer surface.