A method of forming a biocidal halogenated organic/inorganic composite material may include providing at least one inorganic precursor, providing at least one organic agent, precipitating an organic/inorganic composite material by contacting the at least one inorganic precursor with the at least one organic agent, and halogenating the organic/inorganic composite material by contacting the organic/inorganic composite material with a halogen. Also, a halogenated organic/inorganic composite material may include an inorganic composition comprising a metal oxide and a halogenated organic composition. The inorganic composition and the halogenated organic composition are dispersed throughout the composite material.