These data contain the shear modulus and attenuation of Vermont antigorite serpentinite in the seismic "low" frequency range, as functions of oscillation period (ranging from 1 to 1000s) and temperature during staged cooling from 550 degrees C down to room temperature, at a confining pressure of 200 MPa. This dataset is used and fully described/interpreted in the paper: David, E.C., N. Brantut, L.N. Hansen and I. Jackson, Low-frequency measurements of seismic velocity and attenuation in antigorite serpentinite, submitted to Geophys. Res. Lett.