It is important to determine the appropriate law in adsorption reactions to understand the mechanism through the process of adsorption of solute on the surface of solid materials. For this purpose, several models are recognized and fit for experimental data to explain the appropriate kinetics of the adsorption process. The mechanism of metal ions biosorption on dried Ulva lactuca was examined using a variety of analytical methods. The effect of several important factors that influence the adsorption technique was determined. Different batch adsorption tests were carried out as the function of pH, contact time, metal ion concentrations, and Ulva lactuca powder dosage. The optimum conditions for the experiments were performed at a pH value of 6.0, a contact time of 90 minutes and an adsorbent dose of 0.2 mgL-1. The highest removal values for metal ions were 76% for cadmium and 79% for nickel. Kinetic experiments were also applied to estimate the adsorption equilibrium time for the metals investigated. Pseudo-first order, pseudo-second order, and intraparticle diffusion templets were used to create three kinetic templets. For the kinetic investigations, the findings fitted well and illustrated the adsorption kinetics of Cd²⁺ and Ni²⁺ by Ulva Lactuca powder using a pseudo-second order templet with the biomass. This study confirms that Ulva Lactuca, which belongs to green algae, can be used efficiently and at a low cost to remove Cd²⁺ and Ni²⁺ from contaminated water.