The development of knowledge assessment instrument based on problem solving in the electrochemistry. This research aimed to find out the characteristics, teacher responses, and student responses to the problem-based knowledge assessment instrument on the electrochemistry material. The research method used is research and development which consists of four stages namely, research and collection information, product development, field trial, and product revision (Bord & Gall, 2013). This research began by conducting a needs analysis consisting of literature and field studies, product development, initial field trials, and revisions to the trial results. The research instruments are the interview guide of needs analysis, expert validation instruments, and teacher and student response questionnaires. The assessment developed was specifically designed to measure problem-solving skills in students. The research findings indicate that this assessment instrument can be used as a reference for teachers to conduct evaluations at the end of learning. The validity refers to the extent that the instrument measures what it was designed to measure. Content validity measures the extent to which the items that comprise the scale accurately represent or measure the information that is being assessed. Construct validity measures what the calculated scores mean and if they can be generalized. Construct validity uses statistical analyses, such as correlations, to verify the relevance of the questions.