Zeise had at first intended to study medicine, but while attending lectures it became clear that his interests had a broader scientific base; and chemistry remained his favourite subject. He still experimented in Ørsted's Laboratory, but since at that time there was no prospect for a teaching position at the University, he took the pharmacist exam in 1815, later a master's degree (magisterkonferens) and on 21 October 1817 he defended his Doctoral dissertation on 'The effect of Alkalies upon organic substances'. The experimental part of this work he performed in a small laboratory, which in 1816 he had converted from the pharmacy in Slagelse.