The kinetics of the formation of performic acid and peracetic acid were studied in a tubular microreactor. Three different models were considered to estimate the kinetic parameters such as reaction rate constants and activation energies. To increase the accuracy of the models, the hydroxonium ion concentration was derived and applied to all the models. First, a simple plug flow model was used to estimate the kinetic parameters. The results from this predicted the experimental results with a reasonable accuracy. In the next step, a laminar flow model with radial velocity distribution was used to modify the results. This model slightly improved the fit and gave more precise parameters. The Markov chain Monte Carlo (MCMC) analysis showed that all the parameters were well identified with the Markov chain samples centered around the most probable point. Finally, radial diffusion was added to the laminar model, which made the model more complicated and increased simulation time. However, the results proved that the addition of radial diffusion did not improve the model. (C) 2011 Elsevier Ltd. All rights reserved.