The former member of the influential Irish band died Sunday at a hotel in the southern Spanish town of Estepona, where he was vacationing. He was 58.
Spain's Interior Ministry said there were no signs of foul play. The autopsy will be carried out in the nearby city of Malaga, but it was not known when the results would be released.
Moore was born in Belfast, North Ireland in 1952. He was part of the Dublin band, Skid Row before he joined Thin Lizzy in 1973.
He left the band shortly after joining, but he came back to the group four years later and played on the band's "Black Rose" album before going solo once again.
Moore's best known solo hits include "Still Got The Blues, "The Loner" and "Parisienne Walkways," the latter featuring a guest lead vocal by late Lizzy frontman Phil Lynott.
Thin Lizzy had global hits in the 1970s with songs like "The Boys are Back in Town" and "Whiskey in the Jar," before Moore rejoined them. Lynott died in 1986, but with a different lineup the band continues to tour today.
The Associated Press contributed to this report.