The dependence of the burning rate of a solid homogeneous energetic material on curvature of the burning surface is investigated experimentally for the first time. For this purpose we use a double-slit propellant grain which allows realizing the curved burning surface with a controlled curvature. We compare the experimental data with theoretical dependencies obtained in the framework of the Zel'dovich-Novozhilov's theory. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.