Computational thinking (CT) is one of the systematic tools in problem solving and widely accepted as an important skill in the 21st century. This study aimed to identify the effectiveness of the Chemistry Computational Thinking (CT-CHEM) Module on achievement in chemistry. This study also employed a quasi-experimental design with the participation of 85 form four students in Malaysia. The three types of teaching approaches, namely CT-CHEM Module Plugged-in (CTMP), CT-CHEM Module Unplugged + Plugged-in (CTMUP) and conventional method (CM), were systematically designed and implemented. The achievement of students was measured using an achievement test, where validity and reliability were justified and two-way ANCOVA was used to analyse the data. Findings confirmed that the achievement of students in chemistry is significantly higher in the CTMP group as compared with the CTMUP and CM groups. Instead, gender had no significant effect on students' chemistry achievement. This study concludes that when students were exposed to teaching and learning strategies by integrated CT through plugged-in strategy more effective than a combination of plugged-in and unplugged. Plugged-in visualisation activities are more effective in increasing the understanding and achievement of students compared with the combination of plugged-in and unplugged activities. Plugged-in through visualisation activities is more effective than the combination of plugged-in and unplugged. This is because, the abstract concept in electrochemistry is easier to understand by students through the visualisation activity approach using a computer in explaining the important concepts in the topic and because the whole content is interrelated.