Most lanthanide porphyrin derivatives exhibit 'normal' absorption spectra with Q and B bands. The rare earth ions have little effect on the absorption spectra, which are much like those of other closed-shell metalloporphyrins. However, their emission spectra vary according to which lanthanide ion is present. We observe two types of emissions: (i) a line emission arising from the lanthanide ion f-f transitions and (ii) pi-pi* emission from the triplet state of porphyrin. In this Letter, we focus on the emission from gadolinium porphyrin complexes. The oxygen sensitivity was measured in solution and polymeric film. Both intensity and lifetime Stern-Volmer plots were measured. (c) 2006 Elsevier B.V. All rights reserved.