Polystyrene-fullerene compositions containing up to 0.45 mol % (3 wt % fullerene C-60 were investigated. It was established that the addition of fullerene to polystyrene (PS) leads to an increase of molecular packing density and so influences the transport of small molecules through the polymer films. Gas diffusion through films of PS-fullerene compositions is slower than through PS films, and gas separating properties of compositions are higher. Dielectric studies showed that the fullerene is distributed as clusters in the polymer matrix of solid composition prepared from a toluene solution of PS and fullerene. Heating without air to the temperature higher than PS glass transition leads to increasing relaxation time of a-transition in PS of compositions containing >0.15 mol % (1 wt %) fullerene. This effect is caused by rather strong interaction of PS chains via fullerene molecules entered into the PS-fullerene complex.