The dual fluidized bed (DFB) gasifier is a proven technology for steam gasification of woody biomass. In this process, high quality product gas is generated that is rich in H2, CO and other combustible gases. This thesis aims for extending the range of feedstock for the DFB gasification process towards residues and waste. Therefore, different kinds of waste wood, sawdust, SLF-plastics and plastics from municipal solid waste, polymer production residues as well as PE regrind were tested in a 100 kW pilot plant. A focus is set on the influence of specific waste fuel properties on the gasification process, because residues and waste are mostly inhomogeneous, have varying quality and are most commonly challenging fuels for gasification plants. Three aspects are discussed thoroughly: i) fuels with high concentration of nitrogen, sulfur and chlorine, ii) fuels with an increased concentration of fine particles and iii) fuels with extremely high concentration of volatiles. In addition to that, the influence of the fuel feeding position is also evaluated.