Disclosed is a gas turbine blade (1) having a ceramic heat-insulating layer (17). The ceramic heat-insulating layer (17) consists of 10-95% wt. % magnesium aluminate, 5-90 wt. % magnesium oxide and 0-20 wt. % aluminum oxide. Magnesium oxide particles are incorporated into a matrix made of spindle-shaped magnesium aluminate, enabling the thermal expansion coefficient of the ceramic heat-insulating layer (17) to be adapted in a particularly suitable manner to a metallic base body (15) of the gas turbine blade (1). The ceramic heat-insulating layer (17) also has a porosity which is greater that 3 vol. %, thereby guaranteeing sufficiently low heat conductivity.