Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study describes the structural, porosity and morphological changes of porous polymer-derived ceramics obtained by pyrolysis of polysiloxane-clay composites, containing a pore former based on poly(dimethylsiloxane) and nickel acetate as nanostructure inductor. The composites were blended in a steel mold, thermally treated at 950 degrees C and 1500 degrees C (inert atmosphere). The increase of the temperature together with the presence of Ni resulted in more crystalline and porous ceramics and a higher ordering process of C-free phase in the Ni-containing sample. The ceramics revealed a wide pore size distribution, from micro to macropores. At 950 degrees C the ceramic revealed the presence of pores and Ni- and C-rich islands dispersed on the fracture surface. However, at 1500 degrees C, nanowires with large aspect ratio, constituted by Si, C and O elements were generated. Thus, the presence of Ni associated to higher pores amount gave rise to an appropriate environment for the nucleation and growth of SiCO nanowires.254716725Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [05/58460-0, 03/09926-1]CNPq [Proc. 305916/2006-8]