The invention first relates to a composition comprising at least 99 wt. % of 1,1,1,3,3-pentachloropropane and at least one compound selected from a list of additional compounds consisting of dichloropropanes, trichloropropanes, tetrachloropropanes, pentachloropropanes different from 1,1,1,3,3-pentachloropropane, hexachloropropanes, heptachloropropanes, chloropropenes, dichloropropenes, trichloropropenes, tetrachloropropenes, pentachloropropenes and hexachloropropene, the weight content of said compound in the composition being lower than or equal to 500 ppm.