The invention describes solutions containing cellulose and a method of dissolving lignocellulosic materials. In the method, the lignocellulosic material is contacted with a conjugate acid, formed by a strong organic base and a weaker acid, under conditions which are conducive to at least a partial dissolution of the cellulosic components of the lignocellulosic material. It has been found that it is possible to recover at least a portion of the dissolved part of the lignocellulosic material by at least partial dissociation of the conjugate acid. Furthermore it is possible to recover at least a portion of the dissociated organic base and the acid, to form a conjugate acid of the recovered base and acid, and to recycle it for use in the first steps of the method.