Hydrogen concentration measurement with low uncertainty is of great importance in industrial, scientific and commercial applications, which is directly related to the performance of the acquisition system and signal processing. For this purpose, in this paper, it is presented a procedure for the hydrogen concentration in air estimation, using ultrasonic transducers. The time of flight measurement (ToF) is performed using the data fusion procedures based on Maximum Likelihood Estimation, which provides a low measurement uncertainty. Finally, some simulation results are also presented for different levels of hydrogen concentration in air.