Learning chemistry involves algorithmic and conceptual understanding, and students are required to master both of them. This study aims to obtain preliminary data about the algorithmic and conceptual abilities of students in solving chemistry problems. This research is part of development research with Plomp model that focuses on the preliminary investigation stage. The data were collected using test, questionnaire, and an interview involving 50 students of a high school in Banda Aceh. The data were analyzed to find the percentage of students' ability on algorithmic and conceptual understanding. The findings show that 13% of students achieved high algorithmic and high conceptual understanding, 6% of students achieved high algorithmic and low conceptual understanding, and 30% of students achieved low algorithmic understanding. Therefore, it is needed to develop learning materials appropriate to the conditions of students to improve students' algorithmic and conceptual understanding.