Potassium- and sodium-yttrium double tungstate nanopowders co-doped with Yb3+, Ho3+ ions were investigated for their magnetic properties for the first time. We performed the analysis of the compounds using two methods: Electron Paramagnetic Resonance (EPA) and static Magnetic Susceptibility (MS). We have described the symmetry of doped ions environment and corresponding magnetic, optical and structural properties of the above compounds obtained by hydrothermal and Pechini methods. It was performed for the compounds underwent to different calcination temperatures in the range from 600 degrees C to 800 degrees C. For potassium and sodium double tungstates the local symmetry of ytterbium ions is found to be C-2 and does not change with the calcination temperature rise. Based on the finite-size effect we determined the relative size of the nanoparticles agglomeration, observing changes in the values of Curie-Weiss temperature and the intensity of the EPR signal for various calcination temperatures. The magnetic and structural properties of nanoparticles were compared to corresponding ones registered for single crystals and crystalline powders obtained using other methods.