The objective of this paper is to introduce the effect of Soret-Dufour, a higher-order chemical reaction on MHD Casson fluid with a heat source/sink over a vertical plate embedded in a porous medium. The observation reveals different parts of the flow of Casson fluid, heat, and mass transfer. Crank-Nicolson finite difference method utilized for solving Non-dimensional governing partial differential equations. Computations are executed graphically to analyze the change of velocity, temperature, and concentration as well as Skin-friction, Nusselt number, and Sherwood number for different values of parameters Dufour number Du = 0.2, Chemical reaction parameter Kr = 1.2, heat source/sink parameter Q = 2, Schmidt number Sc = 0.6, Soret number Sr = 1.5, order of chemical reaction n = 2, radiation parameter R = 2.2, magnetic parameter M = 4.8, Casson parameter β = 0.4, t = 0.2, Gr = 4, Gm = 7, K = 1.5 and P r = 0.7.