The present study investigates the impact of higher order thinking enhancing techniques as two post-reading strategies on the EFL students' reasoning power as determined by their private speech production. Also, the relationship between the learners' private speech production and their reasoning power is also investigated. In so doing, the study utilizes a quasi-experimental design with 30 participants in each control and experimental groups. The results of the pretest administration indicate that the participants of the two groups are homogenous regarding their language proficiency level as determined by the Babel Test, and their reasoning power as determined by the Watson-Glaser Critical Thinking Appraisal (W-GCTA). The participants in the experimental group are instructed in a way to enhance their reasoning power based on 6 reading comprehension texts. WGCTA's two subtests of deduction and inference making which contain reasoning-gap tasks are utilized as the posttest. While the participants are engaged in carrying out such tasks, their private speech productions are recorded. Data analysis and transcription indicate that private speech which is categorized into 4 classes in this study has a positive and significant influence on the learners' reasoning power. Higher order thinking enhancing techniques are also found to have impact on the experimental group in enhancing their private speech production and subsequently improving their reasoning. The detailed results, discussion, and conclusions of the research are further presented.