From 1837-41 he continued his studies at the art academy in Düsseldorf, which at the time enjoyed widespread international recognition. He studied with and was influenced by his teacher, Theodor Hildebrandt. Here he prepared the well known Hjemvendte fiskere ved den sjællandske kyst (1838). The painting Gustav Vasa taler til dalalmuen i Mora kirke (1841) was sold to a German museum, but was later returned to Christiania. He is associated with the Düsseldorf school of painting.
In the autumn of 1841 he studied in Italy along with his brother Emil. Few of his works from this period remain, except for the picture Napolitansk fisker (1842). Tidemand was preoccupied by Norwegian history, particularly after returning on a journey to Norway. During a journey to 1843 in Hardanger, he met the 18-year-old Hans Gude. This resulted in a close friendship, and eventually they collaborated on several landscape paintings in which Tidemand painted the figures.