Despite the tremendous industrial and scientific interest, hydrogen storage and embrittlement studies still suffer from experimental difficulties in studying diffusible hydrogen effects. As a consequence of the small size and high diffusivity of hydrogen atoms, it is challenging to detect and confirm hydrogen presence in material volumes, let alone investigate corresponding effects on microstructure or damage evolution. To address this need, we developed a novel in situ hydrogen-charging setup which can be applied to high vacuum-based systems such as scanning electron microscopes, to enable high-resolution microstructural analysis during electrochemical hydrogen permeation. In this setup, a hydrogen source is isolated from the objective sample surface in order to avoid the contamination problems from the source and enable analyses of the clean surface during hydrogen charging. Moreover, simultaneous microstructural observation and mechanical testing can be performed during hydrogen charging, by using the developed setup with a miniaturized mechanical tester compatible with high vacuum systems. Here, we demonstrate the capabilities of this experimental approach by carrying out three separate investigations on a duplex stainless steel, a alpha/beta titanium alloy and a ferritic stainless steel. These case studies reveal interesting insights regarding hydrogen effects in these materials. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.