Abstract <p>In the present work we study dynamics of vacancy-type defects in Fe–Ga alloys (galfenols) with gallium content ranging from 16.5 to 33.0 at %. At the beginning, a brief overview of the basic properties and crystal structure of Fe–Ga alloys is presented. Positron annihilation lifetime spectroscopy (PALS), Neutron Diffraction and X-ray diffraction (XRD) methods show a high degree of correlation in changes in the positron lifetime and phase composition of the samples. A comparison of positron data and the results of structural analysis reveal notably different behaviour of defects ordering in alloys with gallium content <i>x</i> higher and lower than 25%. All the alloys quenched at 1000°C demonstrate high concentration of iron monovacancies (&gt;2 × 10⁻⁴ at⁻¹), and positron lifetime linearly grows from ~160 ps at <i>x</i> = 16.5% to ~180 ps at <i>x</i> = 33.0% (tangent 1.5 ps/1%Ga). The observed changes in the positron lifetime correlate with phase composition of the samples.</p>