The results of experimental research concerning removing cyclic ester - lactone from saturated polyester Poles 50/23 have been presented. Short-path, thin-film distillation process was used for removing of lactone from polyester resin, with and without the addition of diethlylene glycol. Fogging tests, determining the tendency for plastic and elastomeric materials to volatize substances which can condense and collect on glass surfaces were made according to DIN 75201. The tests have been made to evaluate materials to be used in automotive or other vehicle interiors. Optimal process parameters which give high product quality were established.