Identification cards include: an 1864 entrance card for the Dusseldorfer Kunstler-Verein Malkasten, a card for the Konigl Akademie der bild Kunste in Munich, 1875-1876, a Carte D'Exposant for the Exposition Universelle of 1889, with a photograph of Mosler, and Mosler's 1892 Ordre National Légion d'Honneur. Passports are for 1863, requesting Mosler's safe passage during the Civil War, and for 1874, for his travel to the American West. Also found is a 1920-1921 entry for Mosler in , an inoculation certificate for Ida Mosler, and a lock of hair.

Letters are primarily written to Mosler with scattered letters written by him. Of particular note is a letter to his parents written from 3 miles outside Corinth, Mississippi on 22 May 1862 in which he describes the scene during the Siege of Corinth following the Battle of Shiloh.

Calling/congratulation cards were sent in response to Mosler's winning the gold medal at the Paris Salon in 1888 and being awarded the Ordre National Légion d'Honneur in 1892.

Correspondents include members of the military regarding his service in 1861-1863 and can be found in several places. A folder of Civil War letters includes Brigadier General R. W. Johnson's request for Mosler to serve as aide-de-camp, and a March 1863 letter from a friend (Bradley?) encamped at Murfreesboro and referring to the building of fortifications there following the Second Battle of Murfreesboro. Letters from include a summary of Mosler's military service from 1861-1863 and a handwritten account of his experiences in September 1861 in and around Louisville, Kentucky. Also found are letters from the United States Army and the Department of the Interior in 1885 introducing Mosler as a "distinguished artist" visiting the West. Included are 3 letters from General Philip Sheridan in which he refers to the "indians, in their uncivilized state," and Mosler's desire "to be able to depict them in a correct light."

Other letters are from museums and art associations, Mosler family members, including Mosler's children, artist Gustave Henry Mosler and Edith Mosler, friends and colleagues including artists James Henry Beard, Julien Dupré, Gabriel Ferrier, François Flameng, Ernest Hébert, William Henry Howe, Heinrich Mücke (history painter and Mosler's Düsseldorf professor), J. Francis Murphy, William Ordway Partridge, and Leon Germain Pelouse, among others. Letters from the Ministere de l'Instruction Publique et des Beaux-Arts include the 1879 purchase certificate for Mosler's painting , and a letter assigning the painting to the Luxembourg Museum.

Letters from the Military Order of the Loyal Legion of the United States confirm Mosler's election as a Member-at-Large to the order in 1896. Also found is a list of autographs of Cincinnati Artists representing a petition to suggest that the Cincinnati Museum purchase Mosler's painting .

Many of the letters are in French and German.

The bulk of the series is arranged alphabetically by correspondent in general files or in named files if there are 5 or more letters from an individual correspondent. A group of files arranged by subject can be found at the beginning of the series.

Of particular note in this series is Mosler's 1862 Civil War diary (with transcript) and two illustrated notebooks, 1862 and 1863, containing diary entries, poems, sketches, financial tallies and names and addresses. The diary contains records of sketches Mosler made for , a narrative of his activities during 1862, financial notes, poems, names and addresses, and several sketches.

Writings by others include biographical accounts of Mosler's life: a Historical Press Association typescript entitled "Henry Mosler, Genre Painter," and a handwritten account of Mosler's career by an unidentified author. Also found are handwritten poems, many of them dedicated to Mosler and/or inspired by his paintings and with accompanying notes and letters. They include poems by J. C. Beard, William J. Dennis ("My Eighty-Third Christmas"), Oscar Edgar (3 poems), François Fertiault (10 poems), Charles Fuster, Alice C. Hall, Roger Miles (2 poems), Berthe Nordez, and Thomas Buchanan Read. Also found is the poem "Acrostic" written by Lt. H. Millard at Shiloh in 1862.

This series includes Library of Congress copyright certificates for Mosler's pictures , , , and , in addition to several life insurance receipts and Sara Mosler's will. Of particular note is a detailed account book of Mosler's personal and professional income and expenses from 1869-1892. There is a gap in the accounting from the end of 1878 to October of 1886 when it resumes with a note written by Mosler explaining that he has found it a "great error not to mark down carefully the daily expenses as it serves two or more purposes-it answers as a 'diary'" and also serves as "something to prevent paying the same bill twice."

The bulk of this series consists of news clippings, primarily about Mosler from American and French newspapers. Also found is a brochure about Mosler and a catalog of an 1897 exhibition of his paintings. Miscellaneous items include an 1887 menu of a "Diner offert a Monsieur Mosler par ses Eleves" from the cafe of the Hotel Del'Elusee.

Artwork by Mosler includes an undated engraving, 4 sketches (1858, 1893, 1898 and undated), a pencil sketch of Sara Mosler on her deathbed in 1903 dedicated to Mosler's children, and an ink drawing for Edith Mosler on her birthday in 1903. Also found are an oil portrait on a scallop shell; an 1890s book that contains sketches by Mosler and various artists including James Henry Beard, E. L. Ravenshaw, Lillian Greene and L. C. Mitchell; and an autograph book belonging to Edith Mosler, 1885, containting sketches by Mosler and others.

Artwork by others includes a handwritten menu with a watercolor illustration signed by Garbriel Ferrier, J. Whitelaw Reid and others, a circa 1880 ink drawing by Leon Germain Pelouse; and an ink drawing of soldiers by E. Hillery.

Photos of Mosler include two of Mosler in his studio, including an 1860 photograph taken in Cincinnati, one photo of Mosler in his studio with a group of students, and an early small framed head portrait.

Photos of family include photos of Mosler and his wife, children, and grandchildren in 2 dismantled albums and 1 bound album. Album 2 also contains a 1906 pencil sketch by Mosler dedicated to Gustave and a watercolor sketch. Photos of others include artists such as Gabriel Ferrier, Ernest Hébert, and Thomas Buchanan Read, art critic Gustave Ollendorf, opera singers Emma Nevada Palmer and Renée Richards, and General R. W. Johnson, who appointed Mosler as aide-de-camp in the Civil War.

Photographs of artwork include 2 albums dedicated to Edith Mosler and Gustave Henry Mosler respectively, containing photos of Mosler's paintings. The album dedicated to Edith also contains one photo of Mosler in his studio.