NaY 1-x (WO₄)₂:Ho 3+ /Yb 3+ phosphors with doping concentrations of Ho 3+ and Yb 3+ (x = Ho 3+ + Yb 3+ , Ho 3+ = 0.05, 0.1, 0.2, and Yb 3+ = 0.2, 0.45) were successfully synthesized via the cyclic microwave-modified sol-gel route; their upconversion properties were investigated. Well-crystallized particles showed a fine and homogeneous morphology with particle sizes of 2-5 ㎛. Under excitation at 980 ㎚, the synthesized particles exhibited yellow emissions based on a strong 550-㎚ emission band in the green region and a very strong 655-㎚ emission band in the red region. The Raman spectra of the doped particles indicated the domination of strong peaks at higher and lower frequencies induced by the incorporation of the Ho 3+ and Yb 3+ elements into the Y 3+ sites in the crystal lattice, which resulted in unit cell shrinkage that accompanied a new phase formation of the WO 4-x group.