<p class="p1"><span class="s1">This study aims to develop a Three-tier Diagnostic Instrument on Chemical Equilibrium (TT-DICE) to diagnose high school students’ misconceptions related to this topic. TT-DICE consists of thirty items, asking for students’ answers, reasonings, and levels of confidence. Three-stages development models developed by Treagust applied in developing TT-DICE. First-stage was a literature study to analyze the main concepts and students’ misconceptions in CE. The next step is the development of the TT-DICE prototype, consisting of item development, preliminary experiments, interviews, and revisions. The third stage of validity checking starts with content validation by experts and practitioners. A field test conducted to determine the reliability and quality variables are supporting TT-DICE items. These variables are Item Validity (IV), Difficulty Level (DL), Discrimination Index (DI), and effectiveness of distractors. Content validity by validators showed that the TT-DICE is valid with a very high category (96.1%). The results of item validity show that 88.9% of the items are valid. Testing of DL, DI, and the effectiveness of distractors in general, shows a good category. The Reliability of the three-tiers TTDICE using Alpha Cronbach is a high and very high category, respectively (0.83, 0.81 & 0.91). The overall validity test results also concluded if the TT-DICE is valid, reliable, and suitable to diagnose misconceptions of Chemical Equilibrium.</span></p>