Cresol–lignin liquors produced as waste from bagasse pulping, at different temperatures (160°–190°C) for 1.5 h and at 170°C for different times (0.75–3 h) were tested to evaluate their reactivity in both alkaline and acidic media toward preparation of cresol–lignin formaldehyde resins. The effects of different polymerization parameters—e.g., time, temperature, ratio of polyphenols to formaldehyde, and reaction medium (acidic or alkaline)—on the yield and properties of produced resins were detected. The yields of the resins produced in alkaline medium are higher than those produced in acidic medium.