Despite the beneficial impact of biofuels on most regulated pollutants and carbon dioxide emission, their combustion results in an increased production of aldehydes which are highly toxic. The oxidation of ac- etaldehyde by oxygen behind reflected shock waves has been investigated by simultaneously recording the emission profiles of excited OH*, CO2* and CH*. Experiments were performed at T5=1295-1580 K and P5=306-404 kPa. Equivalence ratios were Φ=0.5, 1 and 1.5. The argon dilution was held constant at 97%. Five detailed reaction mechanisms were tested with respect to the presently obtained data and those from the literature. The JetSurf model and one obtained using the RMG software over-estimate the present ignition delay-times but reproduce fairly well the data from Yasunaga et al., Wang et al. and Kern et al.. The models from Konnov and Dagaut are in good agreement with the present mea- surements and reproduce some of the results of Yasunaga et al., Wang et al., Kern et al. and Bentz et al.. Overall, the model of Me ́vel predicts a too high reactivity. Analyses have demonstrated the impor- tance of the following reactions: R1: CH3CHO=CH3+ HCO; R2: CH3CHO+CH3=CH3CO+CH4; R3: CH3CHO+H=CH3CO+H2; and R4: CH3CHO+CH3 =CH2HCO+CH4.