About 70nm-thick SrRuO3 and CaRuO3 thin films were deposited by metalorganic chemical vapor deposition (MOCVD) on (0 0 1)SrTiO3 and (0 0 1)[(LaAlO3)(0.3)-(SrAlO3Ta0.5O3)](0.7) (LSAT) substrates at 750 degreesC. SrRuO3 and CaRuO3 thin films were epitaxially grown on both substrates. All films had very smooth surfaces. The detailed crystal structure was investigated by using high-resolution X-ray reciprocal space mapping. The in-plane lattice parameter of SrRuO3 thin film on (0 0 1)SrTiO3 substrate was almost the same as that of SrTiO3, 3.905 Angstrom, and the out-plane lattice parameter was 3.96 Angstrom which was larger than bulk SrRuO3. On the other hand, in the case of SrRuO3 thin film on (0 0 1)LSAT substrates, both the in-plane and out-plane lattice parameters of SrRuO3 film were almost the same as those reported for the bulk. Those of the CaRuO3 thin film on (0 0 1)SrTiO3 was almost the same as the reported values for the bulk, while on (0 0 1)LSAT, the in-plane lattice parameter was almost the same as that of LSAT. These results can be explain the strain remained in the thin films due to the smaller lattice mismatch combination between the thin film and the substrate, i.e. SrRuO3 film on SrTiO3 substrate and CaRuO3 film on LSAT substrate.