A new technique was developed and applied to the study of flame structure and flame-vortex interaction in turbulent premixed flames. Turbulent premixed flames were probed using simultaneous stereo particle image velocimetry (PIV) and a double-pulsed acetone planar laser-induced fluorescence system (PLIF). Two double-pulsed Nd:YAG lasers operating at 532 and 266 nm were used for the PIV and acetone PLIF measurements, respectively, The stereo PIV images were acquired using two double-frame CCD cameras, and two ICCD cameras were used to capture the PLIF signal. The diagnostic system was applied to study turbulent methane-air stoichiometric premixed flames at relatively high Reynolds numbers. Flame merging and the creation of pockets of both products and reactants were detected, and a very strong interaction between the flame front and the vortex structures was suggested in the simultaneous PIV/PLIF images. Double-pulsed PLIF data obtained for different time delays allowed statistical study of flame development. Three-dimensional turbulent fluxes of mean progress variable were obtained. It was shown that the fluxes obey the gradient diffusion hypothesis. The proposed diagnostic increases flexibility and range of measurements available for premixed flames. (c) 2007 The Combustion Institute. Published by Elsevier Inc. All rights reserved.