A novel dendrimer-templating method for the synthesis of CuO nanoparticles and the in situ construction of ordered inorganic-organic CuO-G2Td(COOH)(16) rice-shaped architectures (RSAs) with analogous monocrystalline structures are reported. The primary CuO nanoparticles are linked by the G2Td(COOH)(16) dendrimer. This method provides a way to preserve the original properties of primary CuO nanoparticles in the ordered hybrid nanomaterials by using the 3D rigid polyphenylene dendrimer (G2Td(COOH)(16)) as a space isolation. The primary CuO nanoparticles with diameter of (6.3 +/- 0.4) nm are synthesized via four successive reaction steps starting from the rapid reduction of Cu(NO3)(2) by using NaBH4 as reducer and G2Td(COOH)16 as surfactant. The obtained hybrid CuO-G2Td(COOH)(16) RSA, formed in the last reaction step, possesses a crystal structure analogous to a monocrystal as observed by transmission electron microscopy(TEM). In particular, the formation process of the RSA is monitored by UV-vis, TEM, and X-ray diffraction. Small angle X-ray scattering and Fourier transform infrared I spectroscopy are used to investigate the role of the dendrimer in the RSA formation process. The obtained results illuminate that Cu2+-COO- coordination bonds play an indispensable role in bridging and dispersing the primary CuO nanoparticles to induce and maintain the hybrid RSA. More importantly, the RSA is retained through the Cu2+-COO(-)coordination bonds even with HCl treatment, suggesting that the dendrimers and Cu2+ ions may form rice-shaped polymeric complexes which could template the assembly of CuO nanoparticles towards RSAs. This study highlights the feasibility and flexibility of employing the peculiar dendrimers to in-situ build up hybrid architectures which could further serve as templates, containers or nanoreactors; for the synthesis of other nanomaterials.