The activity profile of a 1:0.30 mixture of Celluclast 1.5L FG and Novozym 188 (Novozymes) was investigated using Whatman #1 filter paper (W1FP) as a single substrate for hydrolysis. The procedure was based on the ability of the enzymes to release total (RS Tot ), insoluble (RS Insol ) and soluble (RS Sol ) reducing sugars from W1FP. RS Insol was used to estimate endoglucanase (EnG) activity whereas exoglucanases (ExG) were assessed by measuring RS Sol in the presence of δ-gluconolactone. Finally, the β-glucosidase (βG) activity was derived from the difference between RS Sol measurements in the presence and absence of δ-gluconolactone. When this analytical procedure was applied to W1FP using 9.64mgmL −1 of the enzyme mixture, the relative contributions of EnG, ExG and βG to the total cellulase activity were 63.28%, 12.02% and 24.70%, respectively. Also, this ratio changed with changes in the enzyme loading, giving a new insight into the synergy that exists among the enzymes.