119Sn Mössbauer spectra of RCo3Sn (R = Gd-Tm) compounds have been measured in the temperature range 4.2-150 K. The TC values obtained from the hyperfine field (Bhf) temperature dependence were found to vary linearly with the de Gennes factor, extrapolating to 30 K for J → 0. Bhf (measured at 4.2 K) was found to depend on the R element in a way that could be explained in terms of rare-earth spin and orbital contributions to the electron polarization, plus a contribution from the Co moments. Additionally, our results provide evidence against a recent claim that RCo3Sn compounds actually belong to the R3Co8Sn4 structure. © 2002 Elsevier Science B.V. All rights reserved.