In educational research, the availability of a validated version of an original instrument in a different language offers the possibility for valid measurements obtained within the specific educational context and in addition it provides the opportunity for valid cross-cultural comparisons. The present study aimed to adapt the Science Motivation Questionnaire II (SMQ II) for application to a different cultural context (Greece), a different age group (secondary school students) and with a focus on chemistry learning. Subsequently, the Greek version of Chemistry Motivation Questionnaire II (Greek CMQ II) was used in order to investigate Greek secondary school students' motivation to learn chemistry for the first time. The sample consisted of 330 secondary school students (163 boys-167 girls), of which 146 were in lower secondary school (14-15 years old) and 184 were in upper secondary school (16-17 years old). Confirmatory factor analyses provided evidence for the validity of Greek CMQ II, as well as for configural, metric and scalar invariance, thus allowing meaningful comparisons between groups. The five motivation components of the original instrument namely grade motivation, career motivation, intrinsic motivation, self-efficacy, and self-determination were confirmed. Gender-based comparisons showed that girls had higher self-determination relative to the boys irrespective of the age group. In addition, girls in lower secondary school had higher career and intrinsic motivation relative to the boys of the same age group. Age-based comparisons showed that lower secondary school students had higher grade motivation relative to upper secondary school students.