In this article, the adaptive chaos synchronization technique is implemented by an electronic
circuit and applied to the hyperchaotic system proposed by Chen et al. We consider the more
realistic and practical case where all the parameters of the master system are unknowns. We propose
and implement an electronic circuit that performs the estimation of the unknown parameters and
the updating of the parameters of the slave system automatically, and hence it achieves the synchronization. To the best of our knowledge, this is the first attempt to implement a circuit that estimates the values of the unknown parameters of chaotic system and achieves synchronization. The proposed circuit has a variety of suitable real applications related to chaos encryption and cryptography. The outputs of the implemented circuits and numerical simulation results are shown to view the performance of the synchronized system and the proposed circuit.