In 1852, he paid a second visit to Algeria, accompanying an archaeological mission, and then completed that minute study of the scenery of the country and of the habits of its people which enabled him to give to his after-work the realistic accuracy that comes from intimate knowledge.
His books include Les Maitres dautrefois ("The Masters of Past Time", 1876), an influential appreciation of Early Netherlandish painting and the Northern Baroque of the Old Masters of Belgium and Holland, Dominique and A Summer in the Sahara. In Les Maitres dautrefois he deals with the complexity of paintings by Rubens, Rembrandt and others, their style and the artists emotions at the time of creating their masterpieces. He is also one of the first "art critics" to approach the subject of The Old Masters from a personal point of view - being a painter himself. He also puts the work in a social, political and economic context, as the Dutch Golden Age painting develops shortly after Holland won its independence. The book developed from articles for journals. Meyer Schapiro has written an essay on Fromentin, "Eugene Fromentin as Critic".