Hamberg, M. Brinker, F. Scholz, M. JACoW Geneva, Switzerland 978-3-95450-177-9 10.18429/JACoW-IBIC2016-WEPG32 English 695-697 WEPG32 laser electron undulator interaction-region resonance Contribution to a conference proceedings 2017 2017-02 http://dx.doi.org/10.18429/JACoW-IBIC2016-WEPG32 http://jacow.org/ibic2016/papers/wepg32.pdf The European XFEL is a 3.4 km long free-electron laser (FEL) which will deliver radiation in the wavelength regime of 0.05 to 4.7 nm. To avoid problems with longitudinal microbunching instabilities a laser heater is implemented. It heats up the electron bunches which will improve the overall brightness level of the FEL. I report the commissioning steps undertaken and the first recorded heating outputs observed in the injector section.