ZnO thin films doped with 0.1 mass% of Gd have been firstly developed with the aim of using as sensitive surfaces for bioanalysis with fluorescent registration. Gd-doped films were prepared by sol-gel and spin coating techniques on monocrystalline silicon supports. Adding Gd3+ ions resulted in a red shift maximum (em = 380 nm) band of ZnO fluorescence by 8-10 nm. Bovine myoglobin (MB) at neutral pH =7 (isoelectric point) was deposited from solutions with concentrations of MB in the interval from 10-6 to 10-12 M on Gd-doped ZnO surfaces by spin coating techniques. This led to 5-8 % fluorescence quenching for 10-6 – 10-10 М MB concentrations and 20 % fluorescence enhancing for the 10-12 M one. © 2019 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.