Two double complex salts containing [RuNO(NO2)4OH]2− anion and [PdL4]2+ cations (L = NH3, Py) were prepared and described by IR-spectroscopy, single crystal and powder XRD. The crystal structure of both compounds is composed by complex palladium cations and complex ruthenium anions. In case of [Pd(NH3)4][RuNO(NO2)4OH] cations and anions are bounded by hydrogen bonds between NH3 and NO2 ligands. The thermal decomposition of the salts was examined in inert and reductive atmospheres. Both the complexes decompose in several stages, first stage according to IR spectroscopy is comprised with the cleavage of OH group of anion, further decomposition undergoes with the removal on NH3 and NO2 ligands. In case of [Pd(NH3)4][RuNO(NO2)4OH] the final temperature of thermolysis in reductive atmosphere is 250–270 °C and the final product corresponds to metastable Pd0.5Ru0.5 solid solution. The composition of metal solid solution was confirmed by XRD and EDX data. Electrochemical and catalytical properties of prepared solid solutions were examined.