Background: Recent studies have associated positive emotions with several variables such as learning, coping strategies or assertive behaviour. The concept of gratitude has been specifically defined as a tendency to recognise and respond to people or situations with grateful emotion. Unfortunately in Latin America, no validated measures of gratitude on different populations are available. The aim of this study was to analyse the psychometric properties of the Gratitude Questionnaire (GQ-6) in two Chilean samples. Methods: Two studies were conducted: the first with 668 high school adolescents (390 women and 278 men, with ages ranging between 12 and 20, and a mean age 15.54 +/- 1.22) and the second with 331 adults (231 women and 100 men, with an average age of 37.59 +/- 12.6). An analysis of the psychometric properties of the GQ-6 scale to determine the validity and reliability of the instrument in Chilean adolescents and adults was performed. Bivariate correlations, multiple regression analyses, exploratory factor analysis (EFA) and Monte Carlo simulations were carried out. Finally, a confirmatory factor analysis (CFA) was performed. Results: A single-factor solution was found in both studies, a 5 item version for the adolescents and 6 items for adults. This factorial solution was invariant across genders. Reliability of the GQ was adequate in both samples (using Cronbach's alpha coefficient). In addition convergent and discriminate validity were assessed. Additionally, a negative correlation between the GQ-5 and depression in adolescents and a positive correlation between the GQ-6 and happiness in adults was found. Conclusions: The GQ is a suitable measure for evaluating a person's disposition toward gratitude in Chilean adolescents and adults. This instrument may contribute to the advancement of the study of positive emotions in Latin America.