This research reports the kinetic studies for acetone and acetaldehyde photoconversion in the gas phase utilizing a scaled-up Photo-CREC-Air unit with TiO2. The inclusion of intermediate species in the reaction network is required for the kinetic modeling of a wide range of oxygenate pollutant concentrations. The proposed "in parallel-series" reaction network encompasses a Langmuir-Hinshelwood (L-H) kinetics including species adsorption and intrinsic reaction parameters. The estimated kinetic parameters provide a successful prediction of various measurable chemical species. It is shown that the proposed kinetic model can be simplified, under low initial model pollutant concentrations. This is critical to avoid model overparameterization. The proposed kinetic model while being restricted to two model pollutants (acetone and acetaldehyde) and one specific photoreactor (e.g. 55.1 L Photo-CREC-Air), provides a framework to establish the photodegradation kinetics of other organic species in air, for larger photoreactor scales. (C) 2017 Elsevier B.V. All rights reserved.