Two thermotolerant, methylotrophic yeast strains, PT44T and S051T, were respectively isolated from a tree exudate and soil collected in Thailand. They were categorized as thermotolerant strains on the basis of their good growth below 20 °C and up to a relatively high temperature (37 °C). The major characteristics of the two strains that place them in the genus Ogataea are the formation of four helmet- or hat-shaped ascospores in a deliquescent ascus that may be produced parthenogenetically or by conjugation between a cell and its bud or between independent cells; multilateral budding; assimilation of nitrate; the presence of ubiquinone Q7; negative for Diazonium blue B colour and urease reactions; and the absence of arthroconidia and ballistoconidia. Analysis of the D1/D2 domains of the large-subunit rDNA sequence revealed that strain PT44T was differentiated from the strain S051T by 25 nucleotide substitutions and 1 gap in 554 nt, which was sufficient to justify the description of two separate species. The closest recognized species in terms of pairwise sequences similarity to PT44T was Pichia (Ogataea) dorogensis, with 13 nucleotide substitutions and 1 gap in 554 nt. Strain S051T was closest to Pichia thermomethanolica, with 7 nucleotide substitutions in 566 nt. Phenotypic characteristics of strains PT44T and S051T allowed them to be differentiated from each other and from the closest related species. On the basis of the above finding, the two strains represent two novel species of the genus Ogataea, for which the names Ogataea chonburiensis sp. nov. (type strain PT44T =BCC 21227T =NBRC 101965T =CBS 10363T) and Ogataea nakhonphanomensis sp. nov. (type strain S051T =BCC 21228T =NBRC 101966T =CBS 10362T) are proposed. We also propose the transfer of two thermotolerant methylotrophic members of the genus Pichia described previously to the genus Ogataea: Pichia siamensis is renamed Ogataea siamensis (Limtong, Srisuk, Yongmanitchai, Kawasaki, Yurimoto, Nakase & Kato) Limtong, Srisuk, Yongmanitchai, Yurimoto & Nakase comb. nov. (type strain JCM 12264T =TISTR 5818T) and Pichia thermomethanolica is renamed Ogataea thermomethanolica (Limtong, Srisuk, Yongmanitchai, Yurimoto, Nakase & Kato) Limtong, Srisuk, Yongmanitchai, Yurimoto & Nakase comb. nov. (type strain CBS 10098T =JCM 12984T =BCC 16875T).