The concept of mathematical problem solving is an important mathematical process in mathematics curricula of education systems worldwide. These math curricula demand that learners are exposed to authentic problems that foster successful problem solving. To attain this very important goal, there must be mathematics teachers well versed in content and the pedagogy of problem solving. This study investigated problem solving process of in-service secondary school teachers in a non-routine problem context. Teachers? written responses were examined based on Polya?s problem solving theory to elucidate their disposition in relation to the problem context. Findings suggest that the in-service teachers exhibit (1) greater lack of understanding of the non-routine problem, (2) insufficient capacity to select appropriate heuristic strategies, and (3) total failure to reach the final "look back" stage. This study recommends in-depth examination of the role of keywords, prior knowledge and experience in mathematical problems, and the importance of written testimonies in metacognition.