The present article is aimed to describe the process of de-veloping critical thinking through a didactic proposal by applying metacognition analysis, results from this work demonstrated that critical thinking skills of a group of eight grade high school students at the public institution “Cristóbal Colón” in the municipality of Morroa, in Su-cre have improved after have implemented the mentioned proposal. The methodological design used in this research work was quasi-experimental which was classified into two main groups as control also as experimental. This study was carried out during the third and fourth academic terms in 2005. The HCTAES Halpern test (2006) was applied in order to assess the above-mentioned groups. Finally the experimental group (8°-2) achieved the highest level com-pared with the control one, according to the range of levels of critical thinking argued by Torres y Beltrán (2001).