The formation of tars in gasifiers based on fluidized- or fixed-bed technology is a major problem in biomass gasification. By pretreating biomass using hydrothermal carbonization (HTC), entrained-flow gasification becomes applicable. Oxygen-blown entrained-flow gasifiers (EFGs) operate at very high process temperatures, leading to an almost tar-free syngas. However, in decentralized small-scale units, preferably air is used as the gasification agent, which, in turn, causes lower gasifier temperatures. The specific impacts of air-blown gasification conditions and fuel properties of biocoal from HTC on tar formation require particular attention. Therefore, in this work, tar formation under air-blown gasification conditions is investigated using solid-phase adsorption at an electrically heated EFG with temperatures of 900–1300 °C and different air/fuel equivalence ratios λ. Furthermore, tars are measured in the hot syngas of an industrial-like autothermal EFG. HTC biocoals of various feedstocks (beech, bioge...