The adsorption of dimethyl(1,5-cyclooctadiene)platinum on porous supports in supercritical carbon dioxide was investigated. Silica gel tablets and a monolithic material were used as the solid support. An experimental method was developed for the investigation of adsorption kinetics where the substance was allowed to dissolve in the supercritical fluid before coming in contact with the solid support. Online UV spectroscopy was used to observe the decrease in bulk concentration in the supercritical solution. Adsorption experiments were carried out at 333 and 353 K at a constant pressure of 15 MPa. Additionally, the solubility of the platinum compound at the experimental conditions was determined. The influence of concentration, temperature, and support material on the adsorption was investigated.