This thesis involves the synthesis and characterisation of sol-gel monoliths doped with Ru(II) polypyridyl complexes. In Chapter 1 an overview of the chemistry of the sol-gel process is given along with an introduction to the photophysical properties of Ru(II) complexes in solution. In the first section of this thesis, the Ru(II) dopants are employed as spectroscopic probes of the sol-gel process, following the reactions as they proceed from the initial sol to the final xerogel. Variations in the photophysical properties of these immobilised complexes were found to accompany changes in the sol-gel microenvironment. As such, these Ru(II) dopants can be employed to yield information on the evolution of the sol-gel reactions. On the one hand, the blue shift in the emission energy of [Ru(bpy)3]2' and [Ru(phen)3]2+ associated with the restrictive nature of the sol-gel matrix as compared to solution, was used to probe the early stages of the sol-gel process. Investigations into a number of parameters (i.e. pH, temperature and water/silane ratio) which effect these reactions were carried out. On the other hand, the photophysical behaviour of the immobilised [Ru(dpp)a]2+ was found to probe the final stages (the drying reactions) of the sol-gel process. This section also investigates the potential application of the acid/base chemistry of a pyridyltriazole complex as a probe of changes in acidity which may occur during the sol-gel process. The final section of this thesis involves using the known information of the sol-gel system to examine the excited state processes of Ru(II) polypyridyl complexes under a novel environment. Chapters 5 and 6 investigate the temperature dependence of the excited-state decay of a range of complexes in solution and in the sol-gel matrix. Significant differences were found depending on the individual complex and also on the nature of the host matrix. These studies suggest that the population of the 3MC state which is responsible for the photodecomposition of these complexes in solution may be inhibited in the solgel matrix and that as such, the photolability of a number of these complexes decreases upon immobilisation.