HOTS is one part of the skills that need to be developed in the 21st Century . This study aims to determine the characteristics of the Fundamental Physics Higher-order Thinking Skill (FundPhysHOTS) test for prospective physics teachers using Item Response Theory (IRT) analysis. This study uses a quantitative approach. 254 prospective physics teachers at West Java and Banten, Indonesia. Data were collected through tests to respond to the FundPhysHOTS test. The FundPhysHOTS test instrument consists of 26 items and Two-Tier Multiple-Choice (TTMC) in form with a polytomous score of 4 categories (1,2,3 and 4). Data analysis includes two stages: the IRT assumption test and then continued with IRT analysis to determine item and ability parameters. The results show that the data are unidimensional and local independence based on empirical data so that the IRT assumption is fulfilled. The IRT analysis used is the generalized partial credit model (GPCM). The results of the item parameter analysis show that all items have good discriminatory power parameters (0.394 < ai < 1.397) and are classified as good. The difficulty level analysis showed that almost all items had good step parameters ( b1 < b2 < b3), with the mean of difficulty index (b mean) in the range of -0.332 to 0.144 and categorized as moderate. The ability ([theta]) of prospective physics teachers is in the range of -3.976 < [theta] < 1.646. Information function analysis shows that the FundPhysHOTS instrument is reliable in measuring ability in this range. This study provides an overview of the analysis of test quality using the polytomous IRT analysis for the benefit of developing the test and developing further studies.