Composite nano-structured calcium silicate materials have been prepared by reaction of a silica-containing solution with calcium ions at elevated pH, characterised and tested in metal adsorption and anti-microbial applications. The material comprises nano-size platelets that self-assemble into particles of about 1-5 mu m in size with an open framework structure. These exhibit a high pore volume and liquid absorption of about 500-600 g oil 100 g(-1) silicate and a high accessible surface area of up to about 600 m(2) g(-1), both of which are controllable in the synthesis process. It has a high whiteness and brightness. XRD shows only short range order. The surface of the nano-size platelets contain both silanol (Si-OH) groups and Ca2+ ions which provide bonding sites for the adsorption of metal cations. As such, the nano-structured calcium silicate exhibits an excellent ability to recover metal cations from solutions such as CU2+ down to the 1 mg kg(-1) level, demonstrating its potential in environmental clean-up applications. Similarly, silver ions can be adsorbed with the resulting nano-structured calcium silicate-silver composites showing excellent antimicrobial activity against Staphylococcus aureus (ATCC 25923) down to very low silver levels of 1 mg kg(-1). The silver cannot be leached out easily. These composite particles can be incorporated into surface coatings, plastics and food packaging as an easily useable, effective and durable anti-microbial agent. (C) 2007 Elsevier B.V. All rights reserved.