Aims This study aimed to identify the most effective antimicrobial agent from a selection of essential oils (EO) and investigate its bactericidal properties against Pseudomonas aeruginosa. Methods and Results The disc diffusion assay and minimal inhibitory/bactericidal concentration tests were used to identify antimicrobial potential. Several oils exhibited antimicrobial effects at concentrations as low as 0 center dot 03% (v/v). Significantly, cinnamon (Cinnamomum zeylanicum) bark EO exhibited a broad-spectrum activity against Gram-negative and Gram-positive bacteria and showed bacteriostatic and bactericidal effects against P. aeruginosa PAO1 at 0 center dot 125% (v/v) and all other tested organisms, including known multidrug resistant species. Time-kill assays and metabolic activity tests showed cinnamon oil to exhibit rapid killing, with bactericidal activity observed in <= 6 min at >= 0 center dot 5% (v/v). Furthermore, scanning electron microscopy and a membrane permeability assay indicated damage to membrane integrity, loss of turgor and cell collapse. Conclusion Cinnamon bark EO is a broad-spectrum antimicrobial agent capable of rapid killing at low concentrations. Significance and Impact of the Study This study provides a sound basis for further investigation of the potential of cinnamon bark EO as an alternative to conventional antimicrobial products due to its fast-acting bactericidal properties at low concentrations.