A novel luminescent lifetime optrode is presented for the detection of gaseous and dissolved oxygen. The optrode utilises ruthenium (4,7-diphenyl-1,10-phenanthroline)3Cl2 as the sensing fluorophore immobilised in a hydrophobic ormosil matrix. The ormosil matrix is synthesised at room temperature from octyltriethoxysilane and methyltriethoxysilane precursors. Investigations of different ormosils were conducted and the most effective one was selected for optrode production. Optrodes were tested for responses to gaseous and dissolved oxygen. Their responses were modelled using traditional two-site or two-exponential methods and feed-forward artificial neural networks. Comparison of the two modelling methodologies is presented and further improvements in modelling and ormosil design are suggested. \circledC Springer-Verlag 2006.