This study aimed to investigate the structure and the validity of the cognitive components of reading in Thai, which is a language with a high degree of grapheme-phoneme correspondence. The participants were 1181 fourth-grade students in 29 schools in Thailand, divided into two subsamples for data analysis. Phoneme isolation, rapid colour naming, rapid number naming, rapid word segmentation, morphological structure and morphological production were developed based on the cognitive theories involved in reading. The reliabilities of the tests ranged from 0.81 to 0.98. The structure of the cognitive components of reading in Thai was examined using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). With subsample 1 (N = 590), the results of EFA support a three-factor structure, measuring morphological awareness, decoding-related and rapid naming skills. With subsample 2 (N = 591), the results of CFA are consistent with the findings of EFA. These findings indicate that the three-factor structure is appropriate to examine the cognitive components of reading in Thai language.