Shock tube ignition delay times have been measured for 3-pentanone at a reflected shock pressure of 1 atm (+/- 2%), in the temperature range 1250-1850 K, at equivalence ratios of 0.5-2.0 for O-2 mixtures in argon with fuel concentrations varying from 0.875 to 1.3125%. Laminar flame speeds have also been measured at an initial pressure of 1 atm over an equivalence ratio range. Complementary to previous studies [Pichon S., Black, G., Chaumeix, N., Yahyaoui, M., Simmie, J. M., Curran, H. J., Donohue, R. Combust. Flame, 2009, 156, 494-504; Serinyel, Z.; Black, G.; Curran, H. J.; Simmie, J. M. Combustion Sci. Tech., 2010, 182, 574-587], laminar flame speeds of 2-butanone have also been measured, and relative reactivities of these ketones have been compared and discussed. A chemical kinetic submechanism describing the oxidation of 3-pentanone has been developed and detailed in this paper; rate constants for unimolecular fuel decomposition reactions have been treated for falloff in pressure with nine-parameter fits using the Troe Formulism. Both compounds treated in this work may be used as fuel tracers, thus further ignition delay time measurements have been carried out by adding 3-pentanone to n-heptane in order to test the effect of the blend on ignition delay timing. It was found that the autoignition characteristics of n-heptane remained unaffected in the presence of 15% 3-pentanone in the fuel, consistent with results obtained using acetone and 2-butanone [Pichon S., Black, G., Chaumeix, N., Yahyaoui, M., Simmie, J. M., Curran, H. J., Donohue, R. Combust. Flame, 2009, 156, 494-504; Serinyel, Z.; Black, G.; Curran, H. J.; Simmie, J. M. Combustion Sci. Tech., 2010, 182, 574-587].