Grid couplings typically comprise flexible, spring-like elements connecting two teethed hubs enclosed in a housing to hold the spring elements and encapsulates grease. Although grid couplings are recognized as versatile solutions for connecting shafts particularly in heavy machinery, the literature on the subject remains sparse. The main objectives of this paper are to investigate the stiffness characteristics, the stress distributions in the spring, the load distributions at the spring/hub teeth contacts and the power losses in aligned and misaligned configurations. Misalignments may lead to uneven load patterns on hub teeth, pressure peaks and partly or totally unloaded teeth. An analytical model is used to calculate the stresses in the spring loops, which compare well with two-dimensional finite element results. A second set of numerical simulations is presented in order to assess the influence of angular and radial misalignments on the grid coupling performance. Finally, the simulations make it possible to estimate the power losses by friction in case of misalignments and confirm that, for realistic values of friction coefficient and positioning error amplitude, the spring-hub contact efficiency remains satisfactory.