Bacteriochlorophylls and carotenois in purple bacteria or photoshynthetic bacteria have important role especially in light harvesting. Both bacteriochlorophylls and carotenoids evolve the photosynthetic uniy (PSU) in protein membrane called light harvesting (LH) complexes and reaction centre (RC). Electronic kinetics of bacteriochloriphylls and carotenoids such as energy trasfer from carotenoids to bacteriochlorophyll or bacteriochlorophylls to carotenoids happen if they are stimulated by light energy. The mechanism of energy transfer from carotenoids to bacteriochlorophylls via singet energy transfer can happen using three channels namely 1 Bu 8314 8594 Qx 1 Bu 8594 Qx dan2 Ag 8594 Qy. On the other hand the energy transfer from bacteriochlorophylls to caro tenoids is directly accepted by carotenoids via triplet energy transfer or indirectly by involving singlet oxigen for mation.