The study sought to produce an emulsion paint binder that will compensate for inadequacy found in traditional polyvinyl acetate binder by optimizing with hydroxylated Guna seed oil (HGSO). Oil was extracted mechanically from Guna seed, and subjected to chemical process of epoxidation to open the carbon to carbon double bond ring for inclusion of hydroxyl group via hydroxylation process. The product-polyol was optimized by copolymerised the HGSO with polyvinyl acetate in series of blend to form a new copolymer binder. Fourier Transformation Infrared (FTIR) was used to assess the chemical change in the chemical processes. The novel PVAc /HGSO copolymer binder was optimised by introducing different concentration of HGSO into the copolymer matrix and examine the crucial paint binder parameters such as density, water solubility, refractive index, melting point, moisture absorptivity, gel time, viscosity, and turbidity. Comparing with permissible value in coating industry, the blend ratio 80: 20 (80% of PVAc and 20% of HGSO) was adopted for the formulation of PVAc/HGSO copolymer binder. The novel PVAc/HGSO copolymer binder resist water excellently with a good optical property and better adhesiveness. Therefore, the novel PVAc/HGSO copolymer binder can be used to formulate an emulsion paint.