The effect of biomass share on gaseous pollutant emissions from fluidized bed co-firing of various biomass fuels with high calorific value coals have extensively been investigated to date. However, effect of co-firing of olive residues with low calorific value lignites having high ash and sulfur contents has not been studied in bubbling fluidized bed combustors. In this study, experimental results of various runs pertaining to gaseous emissions (O2, CO2, CO, SO2, NO, N2O) from METU 0.3 MWt Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) test rig co-firing olive residue with indigenous lignite at different biomass shares are presented. The results reveal that co-firing increases combustion efficiency irrespective of the biomass share and that increase in biomass share reduces N2O and SO2 emissions considerably while increasing CO emission. O-2, CO2 and NO emissions are not found sensitive to increase in biomass share. Olive residues are co-fired with high ash and sulfur containing lignite without any operational problems.