The potential biosorbent of stinky bean peel (Parkia speciosa) (SBP) was investigated for azo dye Procion Red Mx-5B removal due to their accessibility, economically feasible, easy pre-treatment, and non-toxic. This study aims to determine the effect of chemically modified of the SBP, that a massive agricultural waste in Sarawak, to enhance its ability during adsorption of dye. The biosorbent used was dried, ground, and sieved through 600 µm sieve to obtain a similar average size. Impregnation with some chemicals was performed by using ZnCl2, K2CO3, H2SO4 and NaOH for 24 h. The Freundlich, Langmuir, and Temkin techniques were examined to calculate the isotherm data. The result showed that the sorption capacity of the SBP was improved by ZnCl2 modification. The equilibrium data were fitted with the Freundlich model, while the kinetic study was fitted with the pseudo-second-order kinetic model. Further, it was concluded that dyes uptake by biosorbent was based mainly on the role of carboxyl and a hydroxyl group.