The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars , which can be used for asteroseismology . However , for successful seismic modelling it is equally important to have accurate stellar physical parameters . Therefore , supplementary ground-based data are needed . We report the results of the analysis of high-resolution spectroscopic data of A- and F-type stars from the Kepler field , which were obtained with the HERMES spectrograph on the Mercator telescope . We determined spectral types , atmospheric parameters and chemical abundances for a sample of 117 stars . Hydrogen Balmer , Fe i , and Fe ii lines were used to derive effective temperatures , surface gravities , and microturbulent velocities . We determined chemical abundances and projected rotational velocities using a spectrum synthesis technique . The atmospheric parameters obtained were compared with those from the Kepler Input Catalogue ( KIC ) , confirming that the KIC effective temperatures are underestimated for A stars . Effective temperatures calculated by spectral energy distribution fitting are in good agreement with those determined from the spectral line analysis . The analysed sample comprises stars with approximately solar chemical abundances , as well as chemically peculiar stars of the Am , Ap , and \lambda Boo types . The distribution of the projected rotational velocity , v \sin i , is typical for A and F stars and ranges from 8 to about 280 km s ^ { -1 } , with a mean of 134 km s ^ { -1 } .