Contrary to earlier reports, a detailed ferromagnetic resonance (FMR) study in the critical region of Fe90−xCoxZr10alloys with 0≤x≤10 shows that the critical exponents &bgr; and &ggr; for spontaneous magnetization and initial susceptibility, respectively, which characterize the ferromagnetic (FM)‐paramagnetic (PM) phase transition at the Curie temperature,TC, possess values which are close to the three‐dimensional Heisenberg values and areindependentofcomposition. The fraction of spins that participates in the FM‐PM phase transition possesses a value of 11% for the alloy withx=0 and increases with Co concentrationx. The peak‐to‐peak FMR linewidth is governed by the Landau‐Lifshitz‐Gilbert relaxation mechanism in the critical region and the Lande´ splitting factorgand the Gilbert damping parameter &lgr; areindependentof temperature. While &lgr; decreases withx,ghas a constant value of 2.07±0.02.