Multichannel signal separation is a problem frequently encountered in many signal processing and communications applications. A simple and efficient sequential LMS adaptive multichannel signal decoupling algorithm is presented. It is based on minimizing the second commulant for the received mixed signals, although it can also be applied to minimize higher order commulants. The algorithm employs instantaneous signal cross products as estimates for the true cross-correlation based on ensemble averaging. No time averaging is required as in the case of most existing methods. The power of the decoupled output signals may be adjusted to the required levels. The proposed algorithm is fast, computationally efficient and suitable for real time applications. Analysis and simulations are provided to justify the efficiency of the proposed algorithm.