Abstract <p>Diffusible hydrogen (DH) in metals is a part of dissolved hydrogen with high diffusion mobility and the main cause of cold cracking of weld seams and surfaced metal. In this article, the results of technological monitoring of DH in steels are presented. It is found that due to low ultimate permissible concentrations in high-strength steels, measurement methods approbated for weld seams can produce multiple errors in measurements. A technique for measuring DH based on vacuum heating with mass-spectrometric measurement of the hydrogen flow from the sample during its analysis is proposed. It is suggested to separate the flows of DH and more strongly bound hydrogen during vacuum extraction from a sample using an extraction curve. It is shown that when using this technique good convergence of results is observed and the measurement time can be significantly reduced compared to the recommendations of standards for weld seam metals. On the basis of the results of comparison of experimental data and standard requirements, it is established that the activation energy of DH is no more than 0.3 eV. The extraction time of DH at a fixed analysis temperature depends significantly on the size of the steel sample that hydrogen is extracted from. This does not allow one to rely solely on the time and temperature of extraction of DH from bound hydrogen, as recommended by many existing methods for measuring the DH mass fraction. These results can be used during technological monitoring of DH in steels.</p>