A class of binary error-correcting codes, called generalized tensor product codes, is presented with their decoding algorithm. These codes are constructed by combining a number of codes on various extension fields with shorter binary codes. A general algorithm is provided to do bounded distance decoding for these codes. Simply decodable codes such as Wolf's tensor product codes are shown to be special cases of this class of codes. Simply decodable and more efficient codes than Wolf's codes are also included as special cases.