High pressure entrained flow gasification is an efficient technology for the production of a high quality syngas, with minimum amount of hydrocarbons, tar and soot from solid and liquid fuels, as well as suspension fluids. Especially for suspension fuels, e.g. slurries from pyrolysis oil and char as applied in the bioliq® process at KIT, the gasification process is characterized by complex overlapping of different physical and thermo-chemical processes. The energy and conversion efficiency of the gasification process is coupled directly with the process temperature, which is determined by the stoichiometric ratio. The presented work aims on the determination of optimized process conditions in order to maximize syngas yield and quality at lowest possible temperature. Results from experimental investigation at the Research Entrained Flow Gasifier REGA applying mono ethylene glycol as surrogate fuel and a slurry mixed from glycol with 30 wt% of beech wood char are reported. The adiabatic process temperature was varied between 1700 and 1100 °C. Syngas yield and quality are discussed applying characteristic parameters like the yield of CO and H2, carbon conversion and selectivity and the concentration of by-products.