Residual oxygen is regarded as a detrimental factor in the laser-based powder bed fusion of metals process (PBF-LB/M), especially when it comes to highly reactive materials like titanium alloys. Conventional inert shielding gas atmospheres still contain residual oxygen contents. The prevailing concentrations are high enough to cause critical oxidations during processing. By admixing small amounts (<100 ppm) of the highly reactive gas silane to the processing atmosphere, this residual oxygen can be eliminated allowing the establishment of an atmosphere adequate to an extreme high vacuum (XHV). Using a novel specialized machine set-up, the first PBF-LB/M processes of Ti-6Al-4V under silane-doped argon atmosphere were conducted. It is shown that the achieved residual oxygen content of <10^-18 vol-% leads to a significantly reduced bulk oxygen content in the samples without the need to adjust the process parameter settings. A top surface roughness of below S_a = 8.0 µm and high relative density above 99.9 % could be achieved for both the referential argon atmosphere and the silane-doped XHV-adequate atmosphere. The presentation focusses on the innovative machine set-up and the first experimental results. Furthermore, the challenges and opportunities of additive manufacturing in oxygen-free environment are discussed.