Daniel Francois du Toit Malherbe, son of Willem Daniel Malherbe and his wife Hester Magdalena, born du Toit, and brother of Professors I. de V. Malherbe* and F.E.J. Malherbe of Stellenbosch, attended the Paarl Gymnasium and matriculated through the University of the Cape of Good Hope in 1897. He continued his studies at the Normal College, Cape Town, and then at Victoria College, Stellenbosch, passing the university's intermediate examination for the BA degree (equivalent to the first year of study) in 1900. Without completing his degree he went to Germany and was awarded the MA and D. Phil. degrees in chemistry at the Vereinigte Friedrichs-Universitaet in Halle, the latter with a thesis titled Zur Kenntnis des Tertiearbutylbenzols (1905, 33p). Upon his return to the Cape Colony in 1906 he started teaching at a school in Middelburg, Cape Colony. On he basis of his German qualifications the University of the Cape of Good Hope admitted him to its MA degree in 1905.
In December 1907 Malherbe was appointed as the first professor of chemistry in the newly created Pretoria branch of the Transvaal University College (from 1930 the University of Pretoria). In addition to teaching chemistry he was initially responsible also for teaching physics, mathematics and geology. Lecturers for these subjects arrived six months later, so that he could give all his attention to chemistry. A collection of rocks and minerals which he brought with him from Germany formed the core of the collection of the Department of Geology.
Around 1914 Malherbe was an examiner in chemistry at the masters and doctoral levels for the Univeristy of the Cape of Good Hope. As head of the Department of Chemistry at Pretoria he later taught mainly organic chemistry. Initially his lectures were delivered in English only, but from 1917 he began lecturing also in Afrikaans. He was a life-long champion of Afrikaans, a foundation member of the Afrikaanse Taalvereniging (1906), a member of the committee that framed spelling rules for Afrikaans, and a contributor of many articles in early Afrikaans popular magazines. More specifically he was a pioneer in the development of Afrikaans as a technical language and as early as 1918 compiled his Engels-Afrikaanse Skeikundige Terminologie (English and Afrikaans chemical terminology; Bloemfontein, 1918, 32p), one of the first technical word lists in Afrikaans. A few years later he published Organiese gemie (Amsterdam, 1921), a textbook on organic chemistry in Afrikaans. This was followed years later by a major work, Vakwoordeboek - Scientific and Technical Dictionary (1932, 2 vols), compiled with the assistance of 25 subject specialists. By the time he retired in 1941 most of the University's teaching was done in Afrikaans. For some time he served as dean of the science faculty and as a member of the univeristy council, and supported the creation of the faculties of medicine, agricultural sciences, and veterinary science. During the nineteen-twenties he taught general and organic chemistry also to students of the latter faculty.
Malherbe became a member (later a life member) of the South African Association for the Advancement of Science in 1912 and in 1915 was joint secretary of its Section B (which included chemistry). In 1929 he was elected a member of the Suid-Afrikaanse Akademie vir Wetenskap en Kuns and was granted honorary membership in 1963.
At the end of 1941 he retired and settled at Klein Brak River on the Cape south coast. The next year he wrote Afrikaner-volkseenheid (Afrikaner unity; Bloemfontein 1942). He also assisted the compilers of the Woordeboek van die Afrikaanse Taal in the definition of Afrikaans chemistry terms. However, his main interest during retirement was the study of genealogy, leading to the compilation of his monumental Stamregister van die Suid-Afrikaanse volk / Family register of the South African nation (Stellenbosch, 3rd ed., 1966). In 1960 he was awarded an honorary doctorate by the University of Pretoria for his contributions to the development of the university's faculty of science.