Photoproduction of W Bosons at HERA: QCD Corrections

W bosons can be produced in the channels e± p -> W± + X at HERA thus allowing to probe for anomalous trilinear couplings among the gauge bosons. We discuss the NLO QCD corrections to the photoproduction of W bosons with finite transverse momentum at HERA. The higher-order QCD corrections reduce the factorization scale dependence significantly and modify the leading order cross sections by ±O(10%).