Scientific literacy is the ability to read, write, and assist in acquiring competencies that are interrelated to learning science effectively. This research aimed to know the construction, characteristics of items, and quality of developed scientific literacy instrument and to measure the ability of scientific literacy of junior high school students in Tarakan city. This research uses the procedure of test development. The research samples for developing the instrument and measuring ability were 733 students obtained from six junior high schools, which determined by purposive sampling. The data were collected by administering the test and documentation. The data analysis use Winsteps and SPSS computer programs. The results demonstrate the instrument which meets scientific literacy was in the form of 40 items of multiple-choice questions and 6 items of essay questions. The content validity of the test instrument was 0.77, and the Cronbach reliability was 0.85. Both of these criteria were in the high category. The ability of scientific literacy of students in Tarakan city in the knowledge and process dimensions were relatively low. In this case, it should be considered that the development of scientific literacy skills needs to be optimized, especially at the samples.