Thermo-structural studies of the most loaded primary (TCP) and secondary (TCS) collimators of the FCC were performed for both 1 h Beam Lifetime (BLT) and 0.2 h BLT operating conditions. The simulated collimator has a similar design to primary and secondary collimators used in LHC, though a thicker absorber block in Carbon-Fiber-Carbon (CFC) is adopted. For the early conceptual design, a perfectly bonded assembly was assumed in calculations, to increase the stiffness of the structure. The results highlight a considerably high temperature on the absorber block, especially for the TCP in 0.2h BLT (660 °C), but still without failure. In terms of jaw deflection, the highest value is reached for the most loaded secondary collimator and is around 370 µm away from the beam. However, the onset of plasticity appears on the cooling pipes, an issue that could be cured with alternative materials or geometry.