This paper explores two aspects of English spoken by native speakers of Thai: rhythm and the vowel system, and compare each to the substrate language Thai, to target varieties of English, and to two New Englishes in Asia. Data was collected from a group of Thai speakers who participated in an interview in English, and who read a Thai paragraph, and English words, sentences and a paragraph. For rhythm, the paper measured the “Pairwise Variability Index” (nPVI, Grabe and Low 2002) and the proportion of time in an utterance devoted to vowels (%V, Ramus, Nespor and Mehler 1999) of Thai read speech, and English spontaneous and read speech. It was found that the English of Thai speakers had stress-timed values of high nPVI, like Thai and British English (BrE), and low %V, like BrE but not Thai. Neither measure of rhythm resembled New Englishes’ more syllable-timed lower nPVI and high %V. The vowel system of Thai English revealed transfers of both quality and quantity from the substrate, resulting in a system distinct from British, American, and New Englishes.