Laser induced pressure pulse space charge measurements were made on1.5 mm thick plaques of high purity low density polyethylene equipped withvacuum-evaporated aluminium electrodes. Temperature differences up to 20 °C were maintained across the samples, which were subjected to dcfields up to 1.5×107 V m-1. Current density was alsomeasured as a function of temperature and field. Space charge due exclusivelyto the temperature gradient was detected, with density of order 0.01 C m-3. The activation energy associated with the transport ofelectrons through the bulk was calculated as 0.09 eV. However, measurements ofthe temperature dependence of the current in isothermal samples yieldedactivation energies in the range 0.9-1.3 eV. It is deduced that most of thislarger activation energy is associated with charge injection at theelectrodes. Electron mobilities not less than 2×10-12 m2 V-1 s-1 were inferred by combining the space charge and currentdensity measurements.