Adsorption behavior of malachite green from waste water using prosopis juliflora bark carbon was investigated. The effect of contact time, adsorbent dose, solution pH, initial concentration of malachite green and temperature are investigated. Freundlich and Langmuir isotherms are used to determine the adsorption capacity of prosopis juliflora bark carbon as an adsorbent. The entropy change (δS0) values and enthalpy change (δH0) values are calculated from the slope and intercept of the linear plot of lnK0 versus 1/T. The free energy change (δG0) is calculated from the equilibrium constant (K0) value. The equilibrium constant (K0) for the adsorption process is determined from the slope of the plot of ln(qe/ce) against ce. The experimental values of entropy, enthalpy and free energy indicate that the adsorption of malachite green is a physical adsorption. The kinetic studies of malachite green follows pseudo second order and intra-particle diffusion model.