The early stage of hydrogenated amorphous carbon (a-C:H) thin film deposition has been studied by the use of in-situ UV-visible ellipsometry. The a-C:H films were prepared on crystalline silicon (c-Si) mounted on the cathode by capacitively coupled plasma enhanced chemical vapour deposition (CCP-CVD) technique from CH4. The nucleation was observed in a trajectory of ellipsometric angles (Delta, Psi) at the photon energies higher than 4.6 eV. Up to 3 s, the trajectory was explained by using the model based on the cylindrical nucleation, with the radius, height, distance of 6.8 nm, 1.4 nm and 6.0 nm respectively (deposition rate : 0.93 nm s(-1), 2.8 nm in thickness). Then the homogeneous growth takes place with the deposition rate of 0.25 nm s(-1). The deposition rate estimated from the trajectory was 3-4 times larger at the nucleation stage compared with that under homogeneous growth region, These results were consistent with the deposition rates determined by the atomic force microscopy (AFM) measurements. FTIR-Ellipsometry measurements indicate that the a-C:H layer contains a larger amount of C-H, bonds at the early stage of the deposition, which may increase the deposition rate,