The one-pot multicomponent synthesis of 4,4'-arylmethylene-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) was performed effectively by tandem Knoevenagel-Michael reaction of aryl aldehydes and 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one in the presence of a catalytic amount of cellulose sulfuric acid as an environmentally friendly biopolymer-based solid acid catalyst at reflux conditions. All of obtained compounds were characterized by FT IR, ¹H and 13C NMR. This new methodology is of interest due to minimizing the cost operational hazards and environmental pollution, high yields, short reaction time, cost effective and simple work-up.