Amorphous carbon (a-C) thin films were deposited on quartz substrate at different deposition temperature by thermal chemical vapor deposition (CVD) method using natural precursor `camphor oil'. All samples were grown in fixed conditions except the deposition temperature was varied from 400°C to 800°C. The a-C thin films were characterized by using UV-Vis spectroscopy, I-V measurement, Raman spectroscopy and Atomic Force Microscopy (AFM). The UV-Vis analysis was used to obtain the optical band gap. The optical bang gap was decreased from 1.0eV to 0.1eV with the increasing the deposition temperature. The electrical conductivity of a-C thin films increased as the deposition temperature increased. Raman results show that high deposition temperature induced more graphitization in the thin films. The sp2 and sp3-bonded carbon amount in a-C structure could effect the optical band gap of the a-C thin films. These a-C thin films were found to be dependent on the deposition temperature and amount of sp2 and sp3 bonded carbon.