Attribute-based authenticated key exchange (AB-AKE) is a useful primitive that allows a group of users to establish a shared secret key and at the same time enables fine-grained access control. A straightforward approach to design an AB-AKE protocol is to extend a key exchange protocol using attribute-based authentication technique. However, insider security is a challenge security issue for AB-AKE in the multi-party setting and cannot be solved using the straightforward approach. In addition, many existing key exchange protocols for the multiparty setting (e.g., the well-known Burmester-Desmedt protocol) require multiple broadcast rounds to complete the protocol. In this paper, we propose a novel one-round attribute-based key exchange (OAKE) protocol in the multi-party setting. We define the formal security models, including session key security and insider security, for OAKE, and prove the security of the proposed protocol under some standard assumptions in the random oracle model.