The influence of hydrogen bonding and the associated attosecond hole delocalization on the high-order harmonic generation (HHG) process is investigated with the help of hydrogen-bonded binary mixture of acetonitrile and chloroform solvent vapors. We observe a strong enhancement of the HH yield compared to the results obtained with pure samples. We propose that the observed increase of HHG efficiency is due to the presence of hydrogen-bonded binary mixture. Numerical simulations show evidence of the attosecond hole delocalization in the hydrogen-bonded complex of acetonitrile and chloroform. This attosecond hole delocalization contributes to the enhancement of the harmonic yield in the hydrogen-bonded complex. To the best of our knowledge, this is the first report on the sensitivity of the high harmonic generation process to the hydrogen bonding.