Chemical models using complex gas-phase chemistry id one-dimensional Rows have predicted some acetylene/oxygen flame temperatures which exceed the adiabatic flame temperature by over 800 K under fuel-rich, high Row rate conditions. In this work, laser-induced fluorescence was applied to measure the actual temperatures in these flames and to compare them with the predictions of a 1-D model. While the model predicts maximum flame temperatures which are typically within 100 It of the experimentally determined temperatures under low flow rate conditions, at higher Row rates, the actual maximum flame temperature rises much more slowly with increasing Row rate than predicted by the model. The discrepancy between model and experiment reaches 700 K at the highest how rates studied. Tn addition, the experiments suggest that there may be important structural differences between the model-predicted and the experimentally observed flames.