In this study, brown algae modified biomass Padinasanctaecrucis was used for copper (Cu (II)) and cobalt (Co (II)) heavy metals ion adsorption in synthetic wastewater. The effects of solution pH, adsorption efficiency for Cu (II) and Co (II) removal from aqueous solutions were studied. In order to study the kinetic behavior of adsorption, pseudo-first order, pseudo-second order kinetic models, liquid film penetration and Ritchie second-order models were used. The results showed that the second-pseudo kinetic model was able to describe adsorbent behavior in comparison to the other models. Moreover, in order to study adsorbent equilibrium behavior, Langmuir and Freundlich isothermal models were used. Based on Langmuir model, the adsorption capacity of Co (II) and Cu (II) was determined and their values were 13.73 and 13.996 mg/g, respectively. It was shown that both metals ion adsorption process is desirable and adsorption is physical. In this research thermodynamic parameters were also studied in order to determine Gibbs free energy for both ion metals which were negative, indicating metals ions adsorption process is spontaneously and the degree of self-adsorption increases as temperature increases.