PurposeThe purpose of this study is to develop a reliable test metric that can ascertain health literacy as it relates to hypertension in the population of Thailand.Design/methodology/approachOne thousand five hundred patients from hypertension clinics in hospitals under the Ministry of Public Health, Thailand were recruited to this study. The test was developed and divided into three latent variables and four observed variables for health literacy concepts. Indexes of Item-Objective Congruence (IOC) from seven experts and Cronbach’s alpha coefficient of the entire questionnaire were evaluated for content validity and reliability. The Confirmatory Factor Analysis with LISREL also analyzed for construct validity.FindingsThe result illustrates that the Item-Objective Congruence was 0.68, and Cronbach’s alpha coefficient was 0.87. The result also shows that Barlett’s Test of Sphericity was 3129.31 (p < 0.01), and the Kaiser-Meyer-Olkin measure of sampling adequacy was 0.83. The model was fit to empirical data (Chi-square = 0.02).Originality/valueThis study concludes that the Thai Hypertension Health Literacy Assessment Tool (THHLA) created as a result of the study is valid and reliable. The test can be used to evaluate health literacy for hypertension patients in Thailand.