Temperature-dependent neutron powder-diffraction experiments on polycrystalline hexagonal zinc will be performed between 300 K and 25 K. During cooling to low temperatures thermal microstresses will develop due to anisotropic thermal shrinkage, leading to microstrain broadening and modification of the average lattice parameters with respect to the values expected for a single crystal. Evaluation of the hkl-line broadening and of the average lattice parameters will provide quantitative data to be tested against theories for thermal microstress in polycrystals. HRPD is well suited for these experiments due to the possibility to combine large batch sizes (as compared to X-ray diffraction) guaranteeing good crystallite statistics with excellent instrumental resolution as required for line-broadening analysis.