We used optically detected cyclotron resonance (ODCR) at X-band frequency (similar to9.23 GHz) to study the hole effective masses in 6H-SiC. In high-purity 6H-SiC layers, two well-resolved cyclotron resonance (CR) peaks have been observed and attributed to the CR of electrons and holes. In 6H-SiC, the uppermost valence band near its maximum is found to be parabolic with the hole transverse effective mass m(hperpendicular to)=(0.66 +/- 0.02) m(0) and the longitudinal effective mass component M-hparallel to =(1.85 +/- 0.03) m(0). The average of the electron effective mass components in the basal plane-the transversal mass-is determined as m(eperpendicular to)=(0.48 0.02) m(0). With the obtained OJDCR data we can estimate the longitudinal electron effective mass to be in the range 3-6 m(0) depending on the anisotropy of the effective mass in the basal plane.