© 2017, CERN for the benefit of the CMS collaboration. The production cross section of a W boson in association with two b jets is measured using a sample of proton–proton collisions at s=8TeV collected by the CMS experiment at the CERN LHC. The data sample corresponds to an integrated luminosity of 19.8fb-1. The W bosons are reconstructed via their leptonic decays, W → ℓν, where ℓ= μ or e. The fiducial region studied contains exactly one lepton with transverse momentum pTℓ>30GeV and pseudorapidity | ηℓ| < 2.1 , with exactly two b jets with pT>25GeV and | η| < 2.4 and no other jets with pT>25GeV and | η| < 4.7. The cross section is measured to be σ(p p → W (ℓν) +bb¯)=0.64±0.03(stat)±0.10(syst)±0.06(theo)±0.02(lumi)pb, in agreement with standard model predictions.