Phablets, integrated smart devices combining the functionality and characteristics of both tablet PCs and smartphone, have gradually become possible alternatives for smart phones. Therefore, predicting factors which can influence the acceptance of Phablets have become an indispensable task for designing, manufacturing and marketing of novel mobile devices. However, such predictions are not easy. Meanwhile, very few researches tried to study related issues. Therefore, the authors aim to explore and predict the intentions to use and use behaviors of Phablets. The second generation of the Unified Theory of Acceptance and Use of Technology (UTAUT2) is introduced as a theoretic basis. The Rough Sets Theory (RST) will be employed to generate the associated rules based on users' preference for better predicting users' behavior of Phablets adoptions. The analytic results can serve as a basis for concept developments, marketing strategy definitions, and new product designs of the future Phablets.