Nanometer-size titania photocatalysts exhibit variations in chemical properties due to quantum effects on the semiconductor band gap and due to surface and crystalline properties. Degradation of organic molecules appears to be most efficient at particle sizes between 10 and 100 nm for anatase phase catalysts. This study focuses on the early chemical steps of degradation and degradation kinetics of two probe molecules, 4-methoxyresorcinol (MRC) and 1-para-anisyl-1-neopentanol (ANP) when the Millennium PC series anatase titania catalysts are used. These catalysts differ in particle size based on the amount of thermal annealing. Product formation ratios show that primary particle size does not affect the mechanism by which MRC and ANP degrade. Kinetic traces show that loss of ANP and MRC is dependent on particle size, such that PC 50 and PC 100 show the quickest loss of initial concentration of organic molecule and PC 500 shows the slowest degradation.