Transport properties of Topanol CA, [1,1,3-tris(2-methyl-4-hydroxy-5-tert-butyl-phenyl)-butane], were studied in low-density polyethylene (LDPE), in a blend of low-density and linear low-density polyethylenes (LDPE/LLDPE) and in ethylene vinyl acetate copolymer (EVA). The rate of diffusion (D) was evaluated on the free-volume theory basis. A linear relationship was obtained between In D and the reciprocal fractional free volume of the noncrystalline phase of the polymers. Solubility of the additive is higher in EVA than in polyethylene. Compatibility of Topanol CA with ethylene polymers is poor, the measured solubility values depend on the experimental conditions and thermal history of the additive source.