Due to pathogenic bacteria, present as contaminants in food, may survive processing, grow during storage, and cause spoilage of food or diseases to consumers. Hence, this research investigates the bactericidal action of gaseous ozone for the elimination of Bacillus cereus, Salmonella typhi, Klebsiella pneumoniae and Serratia marsecence by surface exposure technique. Under identical treatment conditions, 4.9 and 9.7 g/m³ ozone concentrations decreased bacterial counts by 0.27 to 1.27 log₁₀ cfu/ml depending upon the bacterial species tested. Ozone concentration of 12 g/m³ up to 20 min, a complete log reduction took place in the population of all bacteria species tested. Moreover, at 14.3 g/m³ ozone concentration, a complete log reduction in the number took place at the end of, 2.5 min of S. typhi, 5 min of B. cereus and Serratia marsecence, and 10 min of K. pneumoniae. Ozonation was found to be an effective method to eliminate some of pathogenic microorganisms of great public health concern.