A yellow that has gained some notoriety. Benzimidazolone Yellow is usually found as a bright middle yellow, PY154, but it may also be a deep caramel or orangey brown. It is one of several benzimidazolone yellows, and in general comes highly recommended for lightfastness.

PY154 is a famous benzimidazolone yellow that is sometimes described as an alternative to Aureolin, PY40, also known as cobalt yellow, but having worked with Aureolin, the comparison has a little merit... but not quite enough to say they are similar. The browner form of PY154 could be a bit like Aureolin, which is browner in masstone but more yellow when spread thinly- however Aurolin has a different character. The yellower/brighter form of PY154 may also be recommended as a replacement for other more modern yellows, such as PY73, a Hansa Yellow. Benzimidazolone Yellow, as PY154 tends to have far better lightfastness.

While perhaps not perfect, the lightfastness of PY154 is rated very highly, and artiscreation lists several sources that show all 8's (highest marks) on the Blue Wool Scale for lightfastness testing. Golden chose PY154 to replace one of their other yellow pigments, as described in this article. In Schmincke's watercolors they assign it four out of five stars for lightfastness, with five tending to describe the bulletproof lightfastness of some of the earth tones, so a four means very high in lightfastness.

In terms of health, Monona Rossol's work notes that the chemical in PY154 may metabolize to create something that causes or is related to causing methemoglobinemia.