In this work, we examine the effects of crystallographic orientation and temperature on the mechanical performance of a single crystalline face-centered cubic (FCC) CoCrNi MEA. Uniaxial tensile loadings were applied on the MEA plates oriented along the , , , and  directions at 77 K and 298 K. Our simulation results reveal a strong orientation and temperature effect on the stiffness, strength, and ductility of the MEA. The -oriented plate exhibited the highest elastic modulus, yield stress, and modulus of toughness, demonstrating a strong strain-hardening response; while the -oriented plate produced the lowest corresponding values among the tested cases. At 77K, deformation twinning was the dominant deformation mechanism in the  and -oriented MEA plates, and for the  and -oriented MEA plates, dislocation slip was dominant. At 298K, dislocation slip was the dominant deformation mechanism in all orientations.