Novel tungsten bronze Ba4Gd0.65-xEr0.02YbXNb10O30 (0 <= x <= 0.1) phosphors were synthesized. Their phase and structure were characterized and analyzed by X-ray diffraction (XRD) and Rietveld structural refinements. Under 980 nm excitation, bright frequency up-conversion (FUC) green and weak red emissions were observed. The concentration of Yb3+ had an important influence on the FUC luminescence properties and a possible UC mechanism was proposed. Temperature sensing properties of the Ba4Gd0.55Er0.02Yb0.1Nb10O30 phosphor in the range from 303 to 573 K were obtained by measuring the temperature dependent fluorescence intensity ratio (FIR) of the FUC green emissions at 531 and 554 nm originated from two thermally coupled H-2(11/2) and S-4(3/2) emitting energy levels. A temperature-sensing sensitivity of 0.013K(-1) at 573 K was obtained experimentally and the obtained energy difference Delta E was 971 cm(-1), indicating that this material can be utilized as a promising candidate for the future optical temperature sensors of high accuracy and resolution. (C) 2016 Elsevier Ltd. All rights reserved.