The study was designed to investigate the presentation of core thinking skills in the reading comprehension questions in grades 11A and 12A textbooks with a special emphasis on critical thinking skills. The study further aimed to determine whether certain types of reading comprehension passages, such as expository, narrative, argumentative or persuasive, and descriptive forms, are more likely to provide students with additional practice in critical thinking skills through relevant reading comprehension questions. The study aimed to answer the following research questions: 1. What are the types of reading comprehension passages in the post-basic grades 11A and 12A textbooks? 2. What are the critical thinking skills in the reading comprehension questions in post -basic grades 11 A and 12A textbooks? 3. Do the reading comprehension passages differ with respect to the number of the critical thinking skills they include? To answer the research questions, the following instruments were used to code the reading comprehension passages and questions: 1. An analysis card to code the reading comprehension passages in the previously mentioned four passage types. 2. A text coding guide 3. A second analysis card with a coding guide to code the reading comprehension questions into the thinking skills they include. 4. The coding sheet or form. The study utilised content analysis approach and depended on the analytical framework developed for the study. Two raters were recruited and trained to use the coding guides in order to establish the inter-rater reliability. The researcher recoded the data in order to ensure intra-rater reliability. The obtained data consisted of the frequencies and percentages of the types of reading comprehension passages and the thinking skills required by the reading comprehension questions. The study concluded that heavier emphasis was placed on lower order thinking skills than higher order thinking skills. Moreover, critical thinking skills were poorly presented in the two grades reading comprehension questions. The study also revealed that expository texts were the predominant type of texts. The critical thinking skills in expository texts questions appeared more frequently than those of the narrative texts. Drawing on the results, the study concluded by offering some recommendations to the Ministry of Education in Oman (MOE) and suggestions for future research.