The study investigated the effects of concept -mapping strategy on reflective thinking and academic performance in mole concept among secondary school students in Kaduna state, Nigeria. A total of seventy six (76) SS2 students from two public schools in Giwa education zone were randomly selected from a population of six hundred and forty three (643) SS2 science students using balloting technique. This study adopted pre-test, post-test quasi-experimental-control group designs. Two groups were formed: The Experimental and the Control group. The experimental group students were taught Mole concept using concept-mapping strategy while the control group students were taught the same concept using lecture method. The instruments used for data collection were Mole Concept Performance Test (MCPT), Reflective Thinking Questionnaire (RTQ) and Mole Concept Construction Test (MCCT).The instruments were validated by both chemistry teachers and lecturers in Science Education Department.The Reliability coefficient of MCPT and RTQ were 0.89 and (0.59-0.81) respectively. Pearson Product Moment Correlation was used to determine the reliability coefficient of MCPT,while Cronbach Alpha was used to determine the reliability coefficient of RTQ. Based on the objectives, this study was guided by six research questions and answered using descriptive statistics. Six (6) null hypotheses stated were tested at 0.05 level of significance using statistical t-test, Spearman Rank Correlation (Rho) and Mann-Whitney U test. The results obtained from data analysis showed that students in experimental group performed significantly better than those in control group in both academic performance and level of reflective thinking. Also, there was a significant relationship between the academic performance and reflective thinking of students when taught using concept mapping strategy. Based on the findings of this study it is recommended among others that chemistry teachers should be trained and encouraged by Science Teachers Association of Nigeria to use concept-mapping strategy in teaching chemistry