The capacity of functional groups of soil organic matter to form organometallic complexes may efficiently reduce the risk of migration of toxic ions of heavy metals in the environment. Therefore, a research was conducted to determine the effect of composting and pyrolysis of Miscanthus giganteus biomass on the quality of humic compounds and on the ability of these materials to bind cadmium ions from the solution. Both processes did not cause any significantly favorable changes in fractional composition of the humic compounds of the transformed Miscanthus giganteus biomass. In the case of the unprocessed and composted biomass, changes in cadmium sorption by the materials used in the research, depending on Cd dose and how long the sample was in contact with the solution, had a similar course, which indicates that the responses taking place directly after the application of the solution that contained Cd ions were stable. In the case of thermal processing of Miscanthus giganteus biomass, it was found that Cd content in the solution decreased with time. Lower cadmium concentrations in the extracts after separation of the biomass were determined in the series with biologically transformed Miscanthus giganteus.