The purpose of this research was to examine the internal and the external validation of the rich chemistry multimedia learning environments model to foster scientific thinking.The target group for the internal validation consisted of 9 expert reviewers,1 teacher teaching chemistry in grade 10 and 30 students in grade 10 from Piboonrukpittaya school.The developmental research phase II: model validation was employed in this study.The results were revealed as follows; firstly,for the internal validation,it was found that the model design was consistent with underlined theories based on Instruction Design theories(ID Theories).Secondly,for the external validation,it exposed that the students learning with model have high levels of scientific thinking and achievements.The average scores of scientific thinking test and achievements test were 73.92%over the 70 percent threshold and 75.67%over the 70 percent threshold respectively.The students' opinions toward the rich chemistry multimedia learning environments model to foster scientific thinking were appropriate in all aspects and could enhance students' scientific thinking.