Internal strains that develop between grains during creep of an austenitic stainless steel were measured using in situ neutron diffraction. The secondary creep pre-strained test specimens were considered. Measurements were undertaken before, during and post creep deformation at 550 °C. There was no measurable change of internal strains between grains during in situ creep for 4 h at 550 °C. In addition, the effect of increasing/reducing temperatures in a range from 470 to 550 °C on the internal strains was measured and interpreted with respect to contributions from thermal expansion/contraction. No further internal misfit strains between grains were created when specimen crept during the dwell time at 530, 510, 490 and 470 °C. Results are discussed with respect to (i) the general structure of self-consistent models and (ii) the optimised use of neutron sources for creep studies.