Carbon thin films of n-type semi conducting nature were prepared by spray pyrolysis technique using castor oil as a natural a-carbon precursor.The obtained films were uniform,pinhole free and strongly adherent to the quartz substrates. Studies dealing with the temperature dependence of conductivity revealed the semi conducting nature of the films and Hall measurements indicated the n-type conduction.The low band gap (1.03eV) and semi-conducting nature of these amorphous carbon thin films indicated the future scope of low-cost and high efficiency carbon PV solar cells.