  The diffusivity of hydrogen in cold-rolled pure iron is investigated using
permeation and desorption methods. Electrochemical charging, electro-permeation
and thermal desorption spectroscopy (TDS) experiments are conducted. Firstly,
the relation between the charging current and the hydrogen concentration is
established. Secondly, permeation experiments are conducted at 22, 40 and
67{\deg}C to quantify the diffusivity dependence on temperature. Finally, the
diffusivity is estimated by using two types of desorption experiments and
Fick's law: (i) a `rest time' method, by which we measure the hydrogen content
of samples held at room temperature for different times, and (ii) isothermal
desorption experiments at temperatures ranging from 22 to 80{\deg}C, fitting
the resulting desorption rate versus time curves. Good agreement is obtained
between the isothermal desorption and permeation approaches, with observed
differences discussed and rationalised. Moreover, measured diffusivity values
for cold-rolled pure iron are also found to be comparable to those reported in
the literature. This work demonstrates that isothermal desorption experiments
are a convenient approach to determine hydrogen diffusivity over a wide range
of temperatures, as facilitated by new TDS systems with fast heating rates.
