He is portrayed by Nicholas Rowe.
Jost and his family meet Albert Einstein, as he is to stay at their home in Aarau, Switzerland until he finishes his studies. He also participates in his family's debates at dinner and encourages Albert to join in on the conversation.
After Albert receives a letter approving his German citizenship renouncment, Jost congratulates him. Albert goes on to say that he finds nationalism to be a disease and would rather be world citizen, which Jost again agrees with.
When Albert passes his entrance exam for Zurich Polytechnic, Jost and the Winteler family say their farewells to him.
At the Winteler household in Aarau, Switzerland, Jost and his the family are celebtrating Marie's birthday, with Albert, Maja, and Albert's friend Michele Besso also in attendance. Jost celebrates Albert and his sister for being so close to family, he thanks Albert for bringing Michele over, hoping for him to come to more dinners in the future, and lastly, he thanks Albert for his companionship with Marie.
Before Albert leaves, Jost, who has noticed Albert's recent attitude for Marie, approaches the young scientist and tells him to remember his loyalties to Marie, as he is expecting a great deal from him.
After receiving a letter explaining Albert's breaking up with Marie, Jost takes it upon himself to give the bad news to his daughter and comforts her when she begins to cry.