Multiple Input Multiple Output -Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promising technique for broad - band communication over mobile wireless channels. This paper presents channel estimation methods for Space Time Block Code - Orthogonal Frequency Division Multiplexing (STBC-OFDM) system. Expectation – Maximization based on an iterative algorithm and Decoupled Maximum Likelihood method are used to reduce computational complexity without loss of estimation accuracy. Simulation results show that the effectiveness of the Decoupled Maximum Likelihood method is improved.