Out of a total of 56 paintings in the collection of the Lazar Vozarević Gallery in Sremska Mitrovica, only one Lazar Vozarević painting from 1961, titled “Untitled”, has been subject to atypical degradation that has resulted in damage of completely atypical appearance. Such a problem had never before been noticed in Yugoslavian paintings of the 20th century. Discolored areas were found in various locations on the paint layer of the painting “Untitled” (especially on the lower and central parts of the painting), which disturbed the visual experience of the artistic work. To discover the cause of this discoloration, the composition of the paint layer was investigated, with the assumption that the true cause of degradation was hidden therein. Moreover, this painting belongs to a specific period in Vozarević’s activity, characterized by the use of non-traditional painting materials. To identify pigments from the highly degraded painting “Untitled”, scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM/EDS) and micro-Raman spectroscopy were applied. Lithol red, a synthetic organic pigment known to give paintings a red tone, was identified as the main reason for the painting’s degradation. Lithol red is not only highly light-sensitive but is also chemically unstable, toxic, and sensitive to heat.