The purpose of this study is to describe the characteristics item questions of chemistry national standardized school exam and identify students' difficulties in answering questions. Data collection was carried out by documenting results of the exam in 2018 in Kupang city. The documentation was consisted of 35 multiple choice questions, keys answer and test results of 103 samples students. This research was a descriptive exploratory study. Data analysis was carried out quantitatively and qualitatively. Quantitative data analysis was performed using the classical test theory approach and item response theory with 1 logistical parameter. Qualitative data analysis was carried out to describe the items that were included in the category of difficult levels of distress and poor differentiation, by means of focus group discussion (FGD). The results showed that there were 8 difficult items out of 35 student test items. Base on the results of FGD, the students' difficulties in answering questions were caused by a lack of conceptual understanding in calculating and using complex formulas. The results of the estimated reliability of the questions amounted to 0.83 which showed that chemistry national standardized school exam questions were in the good reliability category.