Seven J?-diketones and their chromium(II1) chelates were chromatographed on four gels with p-dioxanl as eluent, Two poly(viny 'acetate) gels (Merckogel OR-PVA l! 500 and Merckogel OR-PVA 2000) and two pol styrene gels (Bio-Beads S-X8 and Poragel60 A) were investigated_ The distribution coefficients of each compound depend OQ the gel used_ The increasing order of the distribution coefficients of both @diketones and their chromium(II1) chelates depend strongly on the gels, and cannot be simply correlated with the molecular weights of the compounds. The slependence of the distribution coefficients of /i-diketones and their chromium(III) chelates on the gel is different from that of n-alkanes. INTRODUCXLON Gel chromatography has a unique separation mechanism based on the molccular sieve effect, the chromatographic behaviour of a solute compound depending mainly on its molecular size. Gel chromatography, compared with adsorption and partition chromatography, is relatively new, hut it has gained a key position in polymer and biological chemistry, not only as a method of separation but also as a means of determination of the molecular weight and size of solute species. We decided to apply gel chromatography to metal complexes; only a few papers have appeared on this subjectz4, and little is known of the effects of the type of compounds, eluents and gel matrices. We have carried out a systematic investigation of the chromatographic behaviour of acetylacetone and its metal(H) and metaI(HI) chelates, selected as model compounds, on a poly(viny1 acetate) gel with various organic solvents as eluent+'** and the elution behaviour of n-alkanes9 and swelling of the gello in various solvent'systems have also been examined. This paper deals with the effects of gels 02 the chromatographic behaviour of 'ForPartV,seeref. I.