Oxygenated biofuels such as fatty acid methyl esters or ethanol are incorporated in larger and larger amounts into conventional hydrocarbon fuels for use in internal combustion and jet engines. The use of these alternative fuels, along with new engine technology, results in an increased production of toxic pollutants among which aldehydes are the most abundant. The present study focuses on the kinetic modeling of acetaldehyde pyrolysis and oxidation. Based on new ignition delay-time measurements obtained in shock tube and the data from the literature, a comprehensive validation database was assembled. Available kinetic parameters for the most important chemical reactions are reviewed and an updated reaction model is proposed. The new reaction model enables reproducing most of the trends observed experimentally and constitutes an overall improvement as compared to standard detailed chemical models including Aramco 2.0, CaltechMech, and JetSurf.