The research is connected with the solving the problem of rational utilization of agricultural residues by the creation of resource-saving method for their efficient conversion into value-added products. Wheat straw was used in this work in chemical processing. Treatment was carried out with the application of formic/acetic acid mixture. Thus, cellulosic pulp was obtained. The spent solution was used to precipitate lignin. The structure of lignin was investigated. The results indicated that formic/acetic acid treatment was quite effective in isolating cellulose from wheat straw and in recovering lignin. Wheat cellulose is a promising fibrous material for the application in paper industry. Wheat lignin can be considered as a material for biosorbent preparation.