Clara Ponsati, an economist at St Andrews University, handed herself in at an Edinburgh police station this morning after a European arrest warrant was issued by the Madrid authorities.
She is expected to appear from custody at Edinburgh Sheriff Court at 2pm.
The academic was a minister in the devolved Catalan government when it unilaterally declared independence last year following a hugely controversial referendum.
An online fundraiser launched today has since attracted more than 3,000 individual donations.
In a statement, Ponsati said: “I need your urgent support to raise funds for my legal defence against this political prosecution and the systematic attempt to criminalise the desire for independence by more than 2 million voters in Catalonia. The offence I am charged with is punishable by up to 30 years imprisonment.
“It pains me to say this but there is no guarantee of due process in Spain and no guarantee of a right to a fair trial in a country where most members of the Catalan Government are already in prison or in exile.”