In combined Ca-Cu looping applications, maintaining high CO2 uptake is crucial. This study examined three materials with a fixed Cu/Ca ratio of 1.6 to understand the factors influencing CO2 uptake. Testing was conducted over 50 cycles in two looping applications: reduction-carbonation-oxidation for blast furnace gas (BFG) cycle, and carbonation-reduction-oxidation for flue gas (FG) cycle. Multi-grain precipitate material (MGP) consistently maintained its phase distribution, i.e. a combination of mixed Ca-Cu-O phases and separate phases of CaO and CuO, throughout both cycling. MGP showed a peak in CO2 uptake in initial BFG cycles before stabilising, while exhibited stable CO2 uptake in FG cycling. The other two materials, MM1 and MM2, prepared through mixing and calcination at different temperatures (800°C and 950°C respectively), displayed mixed Ca-Cu-O and CuO phases, with no distinct CaO phase. MM1 had a more porous surface, whereas MM2, calcined at 950oC, showed sintering. During both cycling, the phases in MM1 and MM2 evolved towards those in MGP. In BFG cycling, MM1 showed slightly higher stabilised CO2 uptake compared to MM2, likely due to its more porous surface. In FG cycling, MM1 initially experienced a decrease in CO2 uptake, while MM2 showed an increase. However, after the first 5 cycles, MM1 and MM2 stabilised at similar levels of uptake. Surface morphology appeared to influence CO2 uptake while not significantly. Additionally, the stabilised levels of CO2 uptake were less dependent on the initial phase distribution but were governed by the nature of cycling process. BFG cycling gave a much higher uptake.