Since their first synthesis in pure form by Wilson et al. in 1982 the microporous aluminophosphate molecular sieves have been finding importance as catalysts in various chemical reactions in the field of petrochemicals and fine chemicals. Like zeolites they are microporous crystalline materials with high surface area. Their framework consists of alternating oxygen sharing AlO4 and PO4 tetrahedra. Substitution of metal in the aluminophosphate framework is a challenging task which gives rise to the formation of metal substituted aluminophosphate molecular sieves. In these frameworks the metal remains in a highly dispersed state, which is expected to enhance its catalytic activity. The pore sizes and the electronic confinement inside the pores are ideal for guest–host chemistry. They can act as host to number of molecules of interest. This book focuses on the synthesis, characterization and evaluation of the catalytic properties of zirconium and iron incorporated aluminophosphates. Two microporous aluminophosphate framework viz. AEL and AFO have been chosen for metal incorporation, characterised and applied for catalytic reaction.