A review on the chemistry of magnesium porphyrins, which have significant interest owing to the relevance to chlorophyll molecules, is presented with emphasis on bicarbonate adducts of magnesium porphyrin and chlorophyll. The chemistry of 26 unique magnesium porphyrins is described as review articles on synthetic magnesium porphyrins are limited. Interest is given to the electron transfer reactions of magnesium porphyrins in artificial photosynthetic systems. The magnesium porphyrins are described considering coordination chemistry, structural aspects, electronic and electrochemical properties.