The neutron diffusion length in paraffin has been measured by a static technique in the temperature range from 60°C to 130°C. The neutron transport cross section was abstracted from the measured diffusion length. A semiempirical prescription describing the temperature dependence of the neutron transport cross section in paraffin and polyethylene has been derived. The derivation is based on that of the Radkowsky prescription for water. A calculation of the transport cross section in paraffin and polyethylene has been carried out in the temperature range from 20°C to 125°C. The measured transport cross section in paraffin has been compared with that predicted by the prescription. The values agree within 3%. A 14% difference between the values for paraffin and those for water gives credence to the assumption that calculations of the characteristics of plastic moderated critical assemblies can be improved by the use of the proper prescription.