Decentralized exchanges (DEXs) represent a paradigm shift in how digital assets are traded, moving away from traditional centralized exchanges toward peer-to-peer trading on blockchain networks. This study proposes a novel decentralized exchange protocol to address challenges in the security and efficiency of cross-chain cryptocurrency transactions. The research focuses on overcoming the limitations of traditional exchanges by introducing an automated intermediary selection mechanism and strict time limit enforcement. The study employs a rigorous methodology, implementing and testing the protocol on the Remix IDE with the Sepolia test network, utilizing the MetaMask wallet. Algorithm 1, responsible for automated intermediary selection, exhibited efficient operation under Normal Load conditions and demonstrated adaptability by improving processing speed in High Load conditions by maintaining functionality with increased selection time. Algorithm 2, focusing on time limit enforcement, ensured timely completion of transactions under Normal Load, while a slight decrease was observed in High Load conditions. The results highlight the protocol’s success in enhancing security and efficiency in cross-chain transactions. This research contributes to the field of blockchain technology by advancing the understanding of decentralized cross-chain transactions. The findings have implications for improving cryptocurrency trading platforms’ security and user experience. Future work will address scalability, expand asset support, and ensure regulatory compliance in decentralized finance.