Performing distributed software transactional memory (DSTM) applications in a public cloud is investigated in this paper. Transactions are introduced in DSTM for simplifying parallel programming in distributed environments. DSTM is thus a promising alternative to lock-based programming models. Cloud computing attracts attention as a new way for commercial applications and for processing largescale data. However, to our knowledge, there is no study of executing DSTM applications using public clouds. In this paper, we report an experiment on performing DSTM applications in a public cloud. We also try to construct a performance model by adapting a TM performance model to DSTM in order to decide which cloud resources to be chosen in executing DSTM applications. Experimental results show that there are strong and weak points our DSTM model has in deciding machine types and the number of machines for performance.