The production of W bosons decaying into a tau lepton and a neutrino with the tau lepton decaying hadronically has been observed in LHC pp collisions at sqrt(s) = 7 TeV with the CMS detector. The selection criteria provide a statistically significant
signal on the top of QCD multi-jet and electroweak backgrounds. A data-driven method for the estimation of the QCD multi-jet background has been employed.
