Flame front behavior during hydrogen/air deflagration in initially quiescent mixtures in cylindrical envelopes was experimentally studied using ionization gauges and infrared photography. Hydrogen/air mixtures with hydrogen content from 12% to 30% were filled in the polyethylene envelope of 4.5 m(3) and ignited with exploding wire of 5 J energy. The dependences of the flame front position on time were obtained. Dynamics of the flame front was analyzed on harmonic instabilities development. The mechanisms for the creation of turbulence are discussed. Flame front acceleration is analyzed using Kolmogorov law. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.