This study was conducted to investigate the effects of active learning applications, based on constructivism, related to the subject of "Acids and Bases", on high school students' learning achievements and attitudes toward chemistry lesson. For this purpose, a new active learning material was developed by considering students' misconceptions and learning difficulties, and its effects were determined by participation of forty-five students from two different classes which were randomly assigned to experimental (N=21) and control (N=24) groups. The results of the pre-test (KR-20=0.81) showed no significantly differences between groups (F(1-43)=2.66, p>0.05). The instructions of "Acids and Bases" were accomplished with active learning material in the experimental group and with teacher-centred approach in the control group. After the instruction, the 'Acids and Bases Achievement Test' (KR-20=0.79) was administered to determine students' learning achievements, and significantly differences were found between experimental (M=80.76) and control (M=47.83) groups (F(1-43)=102.529, p<0.05). Students' answers to the test and also individual interviews indicated that in contrast to control group, experimental group students had significantly lower proportion of misconceptions about Acids and Bases. Students' answers to the 'Attitude toward Chemistry Lesson Scale' (alpha = 0.81) also reflected positive increases in four dimensions as (i) Interest in chemistry lesson; (ii) Understanding and learning chemistry; (iii) The importance of chemistry in the life, and (iv) Chemistry and occupational choice (F(1-43)= 89.40, p<0.05). (C) 2010 Elsevier Ltd. All rights reserved.