A mercury removal-recovery system was developed for collection of elemental mercury volatilized by biological mercuric ion reduction. Using the mercury removal-recovery system, removal of mercuric chloride from mercury-containing buffer without nutrients by resting cells of mercury-resistant bacterium, Pseudomonas putida PpY101/pSR134 was tested. Optimum temperature, pH, thiol compounds and cell concentration on removal of mercuric chloride were determined, and 92 to 98% of 40 mg Hg l(-1) was recovered in 24 h. The efficiency of mercuric chloride removal from river water and seawater was as high as that observed when using a buffered solution.