Mg-2(Fe, Cr, Ni)H-x synthesis was successfully performed using magnesium hydride and 316L austenitic stainless steel. It was proven that despite being widely used and considered inert, under some conditions, this steel could react with magnesium hydride and be used as a reaction substrate for complex hydride synthesis. The properties of the product are different from those of pure Mg2FeH6, which suggests the partial substitution of iron atoms with chromium and nickel. The influence of milling time on hydrogen content and phase composition was studied and compared to the reference material. It was found to be likely that mechanically induced martensite formed in austenitic stainless steel during ball milling may enable the reaction between steel and magnesium hydride. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.