This study was conducted to compare the biosorption capacities of marine brown algae, Cystoseira barbata, and marine green algae, Caulerpa racemosa. These two algae were chemically modified by crosslinking with glutaraldehyde (GA), H3PO4, and HCl, or only washed with distilled water (DW) for use in equilibrium sorption uptake studies with Cd (II) and Co (II) ions. The pH level of the solution, contact time, initial metal concentration, mixed metal aqueous solution and desorption with different eluents were studied. A Langmuir and Freundlich isotherm analysis of the experimental data showed that the maximum metal uptake for two ions by algae were maintained when crosslinking with GA. The optimum pH value was 6 for C. barbata and 5 for C. racemosa. When the duration of the sorption process was 30 minutes, 0.1 M HCl and 0.1 M HNO3 were the most efficient eluents for these algae. FTIR and SEM analyses were performed as well. Results showed that C. barbata and C. racemosa have great potential for use as an eco-friendly agent in the process of removing Cd (II) and Co (II) ions for characterization of biomass.