Thermotolerant acetic acid bacteria (AAB) are able to be potentially and popularly utilized in many different aspects of fermentation technology, especially processing at high temperature as well as reducing cooling cost. To explore and study the diversity of thermotolerant AAB, AAB were isolated from different kinds of sources in the Mekong Delta (including 13 provinces) of Vietnam. A collection of 178 AAB was isolated and purified from fruits, flowers, cocoa, vinegar, fermented products, alcoholic rice starters and agricultural by-products. The characteristics of morphology, physiology, biochemistry of all AAB isolates were examined and recorded. All isolates were tested for growth at 30, 37, 39, 41, 43, and 45ºC, and for acetic acid tolerant ability at 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 v/v of acetic acid. The AAB isolates were screened for the acid production in agar medium containing bromocresol green 0.01% (w/v) at 30ºC. The fermentation tests were carried out in 100 mL of YPGD medium supplemented 4% (v/v) of ethanol at 30, 37, 38 and 39ºC in shaking incubator for 7 days. The results showed that 97.2% of AAB isolates could grow at 39ºC. The percentage of growing isolates decreased to 88.0%, 66.2% and 37.3% when the incubated temperatures increased to 41, 43 and 45ºC, respectively. A half of tested AAB isolates could grow in the media supplemented with 1.0% (v/v) of acetic acid and it was decreased to 20.4%, 9.86%, 2.82% and 2.11% of AAB isolates in the medium containing 1.5%, 2.0%, 2.5% and 3% (v/v) of acetic acid, respectively. The fermentation capacity of AAB isolates could be classified into 3 groups. In the first group, AAB isolates from fruits, flowers, leaves, and agricultural by-products produced low acetic acid concentrations, about 1.0% at 30ºC and significantly decreased at higher temperature, only 0.3-0.7% (w/v) at 37ºC. The second group, AAB isolated from fermented products including vinegar, and alcoholic starters, could produce acetic acid at 1.84-3.8% (w/v) at 30ºC and slightly decreased at 37ºC (about 1.62-3.28% (w/v)). The last group was the cocoa fermenting AAB isolates, had the highest fermented capacity and be stable with the increasing of temperature. The acetic acid concentrations reached to 3.32-6.48%, 4.08-6.28%, 3.24-6.68% and 3.84-6.53% (w/v) at 30, 37, 38 and 39ºC, respectively. Results of identification based on the 16S rDNA analysis of the 3 superior AAB isolates were Acetobacter pasteurianus. The genetic characteristics of selected predominant isolates and their application for acetic acid fermentation at high temperature at the laboratory-scale and the pilot-scale testing trials are now in progress.