Ag + -and Zn 2+ -exchanged zeolites and clays have been used as coatings and in composites to confer broad-spectrum antimicrobial properties on a range of technical and biomedical materials. 11 Å tobermorite is a bioactive layer lattice ion exchanger whose potential as a carrier for Ag + and Zn 2+ ions in antimicrobial formulations has not yet been explored. In view of this, batch Ag + -and Zn 2+ -exchange kinetics of two structurally distinct synthetic 11 Å tobermorites and their subsequent bactericidal action against Staphylococcus aureus and Pseudomonas aeruginosa are reported. During the exchange reactions, Ag + ions were found to replace labile interlayer cations; whereas, Zn 2+ ions also displaced structural Ca 2+ ions from the tobermorite lattice. In spite of these different mechanisms, a simple pseudo-second-order model provided a suitable description of both exchange processes (R 2 ≥ 0.996). The Ag + -and Zn 2+ -exchanged tobermorite phases exhibited marked bacteriostatic effects against both bacteria, and accordingly, their potential for use as antimicrobial materials for in situ bone tissue regeneration is discussed.