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Two homometallic Coordination Polymers (CPs) with composition [Ln(hfac)₃bipy]_n (Ln³⁺ = Eu³⁺, <b>1</b>, and Tb³⁺, <b>2</b>; hfac = hexafluoroacetylacetonato, bipy = 4,4′-bipyridine) were used to develop a family of ratiometric luminescent thermometers containing Eu³⁺ and Tb³⁺ as red and green emitters, respectively. The thermometric properties of pure CPs and of their mixtures having an Eu³⁺/Tb³⁺ molar ratio of 1:1, 1:3, 1:5, and 1:10 (samples: <b>Eu1Tb1</b>, <b>Eu1Tb3</b>, <b>Eu1Tb5</b>, and <b>Eu1Tb10</b>) were studied in the 83–383 K temperature range. Irrespective of the chemical composition, we observed similar thermometric responses characterized by broad applicative temperature ranges (from 100 to 165 K wide), and high relative thermal sensitivity values (S_r), up to 2.40% K⁻¹, in the physiological temperature range (298–318 K). All samples showed emissions endowed with peculiar and continuous color variation from green (83 K) to red (383 K) that can be exploited to develop a colorimetric temperature indicator. At fixed temperature, the color of the emitted light can be tuned by varying composition and excitation wavelength.