This paper proposes a novel symbol timing estimation technique for multiband orthogonal frequency division multiplexing (MB-OFDM) based ultra wideband system. The symbol timing is estimated in two steps namely, coarse synchronization and fine synchronization. The coarse synchronization is obtained using the correlation between adjacent symbols. A new algorithm is proposed using maximum likelihood concept for achieving fine synchronization. The proposed algorithm overcomes the problem of delayed significant multipath component and exploits inherent frequency diversity in MB-OFDM .The mean square error (MSE) performance of the proposed technique is analyzed using MATLAB simulations for UWB channel models proposed by IEEE 802.15.3a working group for UWB systems. It is proved that the proposed technique has better MSE performance compared to the existing algorithms.