Modified CMPO-PAN production was used and the resulting composite material was tested for purposes of extraction chromatography. A commercially available extraction agent octyl(phenyl)-N,N′-diisobutylcarbamoylmethylphosphine oxide (CMPO) and polyacrylonitrile (PAN) were used. The europium uptake kinetics by composite material was studied in two different nitric acid solutions. The dependences of weight distribution coefficients (Dg) of europium, americium, plutonium, uranium, and neptunium on nitric acid concentration (0.01–5 mol L−1) in the presence of sodium nitrate (0.1 mol L−1) were determined. High Dg-values were found in 0.1–5 M nitric acid for all elements tested. Increase in europium and americium Dg-values with decrease in nitric acid concentration (bellow 0.1 mol L−1) was observed. This behaviour in diluted nitric acid solutions differs from the behaviour of the similar materials with another support. CMPO-PAN composite material was compared with commercially available TRU Resin. Dg-values of the tested elements in all solutions used were higher for CMPO-PAN than for TRU Resin. The retention of the studied elements on CMPO-PAN in hydrochloric acid was made as a screening study.