We report linewidths for f.m.r. in single crystal whiskers of hcp Co. Near room temperature, data were taken at 135, 60 and 37 GHz, Further, the 60 GHz linewidth was studied as a function of temperature down to 4 K. The results are analyzed in terms of a Gilbert‐Landau equation. The relaxation frequency is ∼ 1 × 10 8 / s for 77 ≤ T ≤ 300 K . For T ≲ 70 K the data can be explained if λ is allowed to increase as T is lowered.