SnO2 and SnO2 + Co-porphyrin solids were prepared from SnCl4 in propanol and hydrolyzed to sol. Thermal behavior of samples obtained at 110 °C was studied in the 20–600 °C interval by thermal analysis coupled with mass spectrometry for identification of released species. The original samples maintain residual Sn–OR, Sn–OH and Sn–Cl groups up to 350 °C. The sample doped with 1% Co-porphyrin differs for a significant presence of residual Sn–Cl species, accounting for SnCl4 release in the 300–340 °C range.119Sn solid state NMR analysis reveals disordered SnO2 species in the sample heated at 250 °C and non-uniform SnO6 units in the SnO2 + Co-porphyrin sample at 110 °C, due to persistence of Sn–OR and Sn–OH groups. This complexity is lost at 250 °C. X-ray diffraction analysis confirms all these data. The sensing efficiency of these materials versus alcohols is ascribed to the presence of an …