The hydrothermal synthesis of biomorphous nickel oxide (NiO) with pine template and nickel nitrate precursor is reported here. The morphology, porosity and connectivity of porous products in different length scales were characterized by field emission scanning electron microscopy, X-ray diffraction and nitrogen adsorption measurements. Their porous structures were found to be hierarchical from 1 up to 25 mu m (in micrometer scale) and from 2 nm to 60 nm (in nanometer scale). Furthermore, depending on the heat-treatment temperatures, the porosity of the pine-templated NiO can be designed.