The presence of chlorine (Cl) in biomass or pulverized coal poses a significant challenge inchemical looping combustion (CLC), as it can corrode both oxygen carriers and the boiler′s heatexchange equipment. Despite this, there is a notable lack of research focused on hydrochloric acid(HCl) in CLC processes. This study explores the development of a composite oxygen carrier aimed atEnergy Environmental Protectionenhancing chlorine fixation and corrosion resistance. To achieve this, two adsorbents, Ca-based and Ba-based, were selected. The composite oxygen carrier was synthesized using the sol-gel method, and abatch fluidized bed served as the experimental setup for biomass CLC experiments. The studyinvestigated the effects of Ca and Ba doping on the combustion characteristics and chlorine bonding ofCu-based oxygen carriers. The results indicate that alkaline earth metals in Ca-Cu and Ba-Cuformulations preferentially form stable chlorides with HCl, enhancing the lattice oxygen activity of thecarriers and promoting gas-solid reactions for chlorine capture. Notably, the peak CO production andpeak height for Ca-Cu and Ba-Cu carriers were significantly higher than those for standard Cu oxygencarriers. Additionally, Ca/Ba doping improved the gasification of biomass coke, with no detectablelevels of H and CH during the reduction stage, suggesting more complete conversion of these gases byoxygen carriers. The peak CO concentrations were measured at 0.08%, 0.07%, and 0.06% for Ca-Cu,Ba-Cu, and Cu carriers, indicating enhanced CO conversion efficiency. Further experiments assessedthe impact of temperature and oxygen-fuel ratio on combustion and dechlorination performance.Increasing the temperature from 800 ℃ to 900 ℃ resulted in a combustion efficiency rise for the Cuoxygen carrier from 87.0% ± 0.5% to 94.7% ± 0.4%, representing a maximum increase of 8.6%.Conversely, the combustion efficiency of the Ca oxygen carrier decreased slightly from 95.6% ± 0.6%to 95.2% ± 0.1%. In contrast, the Ba oxygen carrier showed a significant improvement, increasing from88.0% ± 1.6% to 94.7% ± 0.4%, with a maximum increase of 8.7%. In biomass CLC, Ca-Cu oxygencarriers demonstrated superior temperature stability, while the combustion efficiency of Ba-Cu carrierswas significantly affected by temperature changes. When the oxygen-fuel ratio was raised from 1.5 to2.0, the chlorine fixation efficiency for Cu carriers increased from 84.3% ± 6.3% to 96.3% ± 1.2%. BothCa- and Ba-based oxygen carriers maintained 100% chlorine fixation efficiency, suggesting that loweroxygen-fuel ratios could be utilized in biomass dechlorination processes, thereby reducing carboncapture operating costs. Moreover, doping with Ca and Ba increased the specific surface area and porevolume of the oxygen carriers, increasing the contact area with biomass and thereby stabilizing theirperformance in CLC. This study helps to understand the chlorine fixation characteristics of alkalineearth metals, promoting the development and application of chlorine-resistant carriers.