1799, he graduated from the University of Copenhagen with a doctorate in philosophy. Oster's main contribution to science is to discover the magnetic effect caused by current. According to his own account, this discovery was made in a speech in the spring of 1820 and announced in the summer of the same year. In fact, as early as 18 12, he put forward the connection between electricity and magnetism in his article "Opinions on Chemical Laws". The discovery of magnetic effect is of great significance in science and promotes the rapid development of electromagnetism.

After many failures, Oster adopted an exquisite manometer in 1822 to ensure that the increased pressure acts on the inside and outside of the water container, and obtained quite accurate data of water compressibility for the first time. 1823, according to the research results of thermocouple junction, it is concluded that this junction can generate higher current at a much lower potential difference than that of photovoltaic cells. He also made some important improvements to the Coulomb torsion balance.

Oster's main works include experiments on electrical effects.