In order to explain chemistry subjects by linking them to everyday life and accordingly, to improve the quality of education, context-based learning has come into use widely in chemistry teaching recently. The aim of this study is to develop a scale to determine secondary school students' motivations towards chemistry activities supported with context-based learning. Validity and reliability analysis of the scale were done with the participation of 525 high school students. To determine the structural validity of the scale, exploratory factor analysis was done. The factor analysis concluded that the scale had a three-factor structure with 20 items. Cronbach Alpha internal consistency coefficient of the scale was calculated to be 0.91. Cronbach Alpha internal consistency coefficients of sub dimensions were found to be 0,84; 0,80 and 0.81 respectively. In the light of the findings of this study, the scale developed is concluded to be of use in determining high school students' motivations towards context-based chemistry.