This research aimed to identify the effects of inquiry-based learning on the conceptual understanding of grade seven students about substances in chemistry. This research was quasi-experimental design. There were total of 48 respondents in Dilchibo primary school of grade seventh section ‘A’ students and their chemistry teacher being involved as the subjects of the study. The researcher was used both quantitative and qualitative data. The quantitative data was gathered through pre-posttests. These tests were used to determine gains in content knowledge and ability to solve problems. Multidimensional observation check list was used to measure qualitative and quantitative data regarding the students’ and teacher’s experience about practicing enquiry based learning strategy in chemistry class. qualitative data was gathered through Questioners and interviews to measure the students and teacher’s perception about learning chemistry through utilizing inquiry based learning approach, and the challenge that affect implementation of IBL were also identified through interview and observation while the researcher practicing inquiry activities. The research discovered findings show that both students and their chemistry teacher have insufficient experience of practicing IBL, the teacher have positive perception towards implementation of IBL, the students perception before intervention was negative but after the intervention their perception towards IBL was clanged, the main challenges that affect application of IBL were identified such as large class size, shortage of time and lack of resources. And there is a significant difference in terms of conceptual understanding through utilizing inquiry-based learning approach and lecture method, inquiry learning approach with appropriate scaffolding is potential to be a significant strategy for improving elementary school students’ conceptual understanding. The findings suggested that the inquiry based learning approach have implications as a practical and effective teaching and learning method in enhancing students to develop their conceptual understanding about substances in chemistry.