The objective of this study was to investigate the use of manganese oxide nanocomposite to remove Cd(II) ions from aqueous phase. The adsorption behavior was studied as a function of adsorbent mass, solution pH, and contact time. The response surface methodology (RSM) by Box–Behnken design (BBD) was employed to evaluate the effects of these three parameters on the removal ratio of the Cd(II) ions. In process optimization, maximum removal of Cd(II) ions was achieved as 100% with adsorbent mass 1g, solution pH of 8.0, and contact time of 27 min. The kinetics of adsorption process by comparative analyses of the applicability of four kinetic models, pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich kinetic model was investigated. The adsorption kinetics of Cd(II) ions was well fitted with the pseudo-second order kinetic model. Equilibrium isotherm studies revealed that Langmuir and Redlich–Peterson isotherm models fitted better with the adsorption data in describing the adsorption behavior. Adsorption of Cd(II) ions on adsorbent is favorably influenced by an increase in the temperature of the operation. Values of the change in standard heat of adsorption (ΔH°), and entropy (ΔS°) were positive. The negative value of change in standard Gibbs free energy (ΔG°), indicates the feasible and spontaneous of Cd(II) ions on manganese oxide nanocomposite.