The geometry of the source of hydrogen leakage is essential in forming hydrogen flow and distribution in air. For example, if the geometry of the source is circular, the behavior of leakage flow becomes axisymmetric and a radial jet is constructed. On the other hand, if the geometry of the source is planar, the behavior of hydrogen leakage becomes planar and a planar jet is constructed. Throughout this article, the problem of momentum-dominated regime of a planar slow-leak hydrogen air jet resulting from a hydrogen leakage from a planar source is considered. We derive a set of analytical expressions for selected physical turbulent properties. Several quantities of interest are obtained, including the cross-stream velocity, the Reynolds stresses, the velocity-concentration correlation, the dominant turbulent kinetic energy production term, the turbulent eddy viscosity, the turbulent eddy diffusivity, and the turbulent Schmidt number. Moreover, the normalized jet-feed material density and the normalized momentum flux density are correlated. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.