We examined mesoporous TiO2 as a photosensitizer and template for creating hybrid TiO2-polypyrrole materials. Optical excitation or mesoporous TiO2 was used to generate the electronic potential necessary for the oxidation and polymerization of the pyrrole monomer. The photopolymerization process was monitored by the quartz crystal microbalance. nitrogen sorption, and thermogravimetric techniques. In situ generation of polypyrrole was observed to be self-limiting alter approximately 20-30% filling or the mesoporous TiO2 network. In situ generation of a complementary phase by means of chit rile transfer from an active host phase represents an alternative means of assembling hybrid inorganic organic materials with potential applications ranging from electrocatalysis to photovoltaics.