Auctions are especially useful in cases where there are no organized and standardized markets. They have a great application in commerce but also in finance. The usual way of conducting them involves an intermediary who must be fully trusted by all participants. The involvement of a third party in the auction process creates inefficiency for the other participants with high costs and often a lack of transparency and flexibility. For these reasons, we are considering the use of blockchain technology and its fundamental features in the auction process. After analyzing the technology and the existing relevant literature, we came to the conclusion that a properly designed blockchain can cover many of the existing problems of centralized auctions. In addition, we present a Double Auction (DA) implemented in a blockchain network, while in our effort to go one step further, we propose, based on the foundations we had laid earlier, a complex combinatorial auction (CA) for which we designed our own Generalized Algorithm (GCAS) to solve the problem of item allocation (General Combinatorial Auction Solver).