This work deals with the determination of the laminar burning velocity and introduces the Markstein length of powder-air mixtures. A powder burner was used to stabilize laminar cornstarch-air dust flames and the laminar burning velocity was determined by means of laser Doppler anemometry. The dust concentration was varied from 0.26 to 0.38 kg m(-3). The measured laminar burning velocities were found to be sensitive to the shape of the flame. With the same dust concentration, parabolic flames were found to have a laminar burning velocity, which was almost twice that of a planar flame (ca. 30 cm s(-1) for the latter as compared with ca. 54 cm s(-1) for the former). From this discrepancy and the flame curvature, the Markstein length could be determined. It was found to have a value of 11.0 mm. This Markstein length was subsequently used to correct the measured laminar burning velocities at various dust concentrations in order to obtain the unstretched laminar burning velocity. The unstretched laminar burning velocity lies between 15 and 30 cm s(-1) and is thought to be a property of the dust and of the concentration. (C) 2002 Elsevier Science B.V. All rights reserved.