This paper describes creating the new variable mode of operation for block cipher, and it also discusses possibilities of using the deterministic chaos in this mode of operation. It discusses the use of deterministic chaos to make the mode of operation variable and pseudo-random. Main idea of this article is to design the mode of operation dependent on all parts of encryption process as plaintext, cipher text and previous used key, and to create the function controlled by deterministic chaos, where the chaotic system has role of pseudo-random number generator, which manages the rules how these parts are used. The logistic map as the simple deterministic chaos system is used for showing the example of the application. © Springer Internationa...