Lignin, a bio-originated polymer, is being explored as an alternative to nonrenewable fossil resources. It is obtained from biomass during pulping and is mostly burned for energy. In most kraft pulp lines, residual lignin in the pulp is oxidized and solubilized during an oxygen delignification step. This study proposes an isolation method for lignin solubilized during oxygen delignification, which we refer to as "oxlignin", and explores its structural characteristics and properties. The study found acid precipitation to be an effective method for partially isolating oxlignin from the oxygen delignification step. Various analytical methods were employed, including UV-vis absorption analysis,