Paul Berthoud was a Swiss missionary and a Tsonga and Ronga linguist. After his education in the theological faculty of the Vaudois Free Church at Lausanne, Switzerland, he spent two years in Edinburgh studying medicine and English. He and Ernest Creux (a fellow student in theology) and their wives arrived at Morija, Lesotho, in February 1873 to work under the direction of the Paris Evangelical Mission at their station Hermon. They were the first missionaries of the churches of French Switserland (La Suisse Romande). In 1875 they moved to the Transvaal and established the Valdezia mission at Spelonken. Despite some opposition from President T.F. Burgers and his government their work went well and Berthoud became known for his medical skills among both the indigenous population and the white farmers. Following the death of his wife Eugenie and their three children from malaria in 1879 he returned to Switzerland on leave during 1880-1884 and married his second wife, Ruth Junod, sister of H.A. Junod*. In 1887, after a few more years at Spelonken, he set up the mission station Rikatla on the Mozambique coastal plane. Other stations soon followed, including one at Lourenco Marques (now Maputo). Berthoud visited Switzerland again from 1894 to 1896. His second wife died in 1901, and he retired to Switzerland in 1903. Despite his poor health he returned to Maputo in 1906 to assist the mission and spent most of 1907 to 1909 at the Rikatla and Tembe missions. He visited Switzerland again in 1913-1914. He was survived by his third wife, Emma Mathilda Schlub.
Berthoud's numerous publications between 1883 and 1929 include mainly bible translations, hymns and grammatical studies of Gwamba (Tsonga) and Ronga. He was a pioneer in the study of these two languages and his linguistic contributions to Tsonga literature were of particular significance.
His first contribution to science consisted of observations on the geography and geology of southern Africa. These observations were extracted from his letters and published by E. Renevier as "Remarques geographiques et geologiques sur le Sud de l'Afrique" in the Bulletin de la Societe des Sciences Naturelles (Lausanne, 1874-1875). More important were his systematic meteorological observations at Maputo from 1890 to 1901. These were summarised in a series of about 20 notes in the Boletin da Sociedade de Geographia de Lisboa (1902-1906, Vol. 20-24). The accompanying tables contain three-hourly day-time observations of air temperature, humidity, wind speed, wind direction, cloudiness and rainfall, for the period July 1899 to December 1901; annual mean values for 1890-1901 are given in the last two notes. In a short paper in the same journal in 1902 he compared his observations for the three months November 1898 to January 1899 to observations made at Antananarivo, Madagascar. The next year, in another short paper in the same journal on "Meteorologie de Lourenco Marques" he reviewed his observations for the period July 1891 to June 1901. In 1909 his observations formed the basis of a German article by J. von Hann* on the climate of Maputo.