A new species of silurid catfish in the genus Wallago is described from the Mekong River drainage in Cambodia, Laos and Thailand, and the Chao Phraya River drainage in Thailand. Wallago micropogon can be distinguished from congeners in having a unique combination of the following characters: pelvic-fin length 8.9–10.6% SL, pectoral-spine length 14.3–16.7% SL, eye diameter 8.7–10.1% HL, maxillary barbels reaching to middle of pectoral-fin base, branchiostegal rays 14–16, gill rakers on first branchial arch 14–16, anal-fin rays 68–73, vertebrae 63–65, brown color with few pale patches on sides of body, gape extending to anterior margin of eye, and a broadly rounded pectoral fin with fourth branched ray longest.