Emotional intelligence (EI) is a fundamental skill related to different aspects of human life, such as psychological well-being or mood states. The present study has a triple objective: first, to explore the psychometric properties of the TMMS-24 in three Spanish-speaking countries (Argentina, Ecuador, and Spain); second, to examine the relation of EI with mood and avoidance of responsibility; and finally, to analyse the influence of sex, age and national differences on EI. The relevance of this study is given by the need for tools to assess EI in different cultures. A sample of 1048 adults (Mage = 21.11 years, SD = 5.84; 52.3% male) was selected by convenience sampling. The psychometric properties of the TMMS-24 were adequate, and the Spanish sample showed lower levels of EI than the Argentinian and Ecuadorian ones. EI was associated with mood and the avoidance of responsibility, with higher levels in women in all cases. Regarding the national and sex-specific differences, the Spanish sample showed significant differences in attention and repair, with men exhibiting higher scores in attention and women having higher scores in repair. In the Argentinean sample, no significant differences were found, and in the Ecuadorian one, women presented higher scores in attention than men. The TMMS-24 can be considered a useful, practical tool to assess EI in adults in different cultures and with different languages.