Residual biomass waste is used as an efficient and low-cost means of removing heavy metals (nickel, cobalt, chromium, lead, mercury, arsenic, among others) from wastewater, so it is important to evaluate the potential of cocoa shell waste (Theobroma cacao L.), with three particle sizes (0.35, 0.5 and 1 mm), as an adsorber of cadmium ions and lead in aqueous solution (100 ppm) in a batch system, that was the objective of this research. It was hypothesized that the smaller the particle size, the higher the percentage of removal of cadmium and lead ions. A factorial experimental design with three levels of variation and two study factors (particle size and initial metal concentration) was implemented, carrying out 9 experiments per metal, for a total of 18. Plant segments were washed and dried, then adsorption was determined. The process of removal of Cd (II) and Pb (II) ions was favored by particles of 0.35 mm, with which the maximum percentage (95 and 86%) of removal of Cd and Pb was obtained. The kinetic model that best fitted the experimental adsorption data was Elovich and the isothermal model that best described the results was that proposed by Freundlich. It is concluded from the results obtained in this study that cocoa shells 1112 Candelaria Tejada-Tovar et al.have great potential for removal of Cd and Pb in aqueous solutions in a satisfactory manner.