Display omitted •Novel Li2−2xK2xPbP2O7 system has been synthesized through the conventional melt-quenching method.•The amorphous and crystalline characteristics have been investigated using both XRD and DSC analyses.•The thermal characteristics have been investigated via the DSC technique.•The composition effect on the glass structure before and after crystallization has been explored through spectroscopic studies.•Dielectric relaxation phenomenon has been evidenced for all samples. Novel Li2−2xK2xPbP2O7 system (x = 0, 0.2, 0.4, 0.6, 0.8, and 1 mol%) was synthesized through the conventional melt-quenching method. The amorphous and crystalline characteristics of the resulting compounds were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The study assessed the effect of potassium doping on thermal parameters, including glass transition temperature (Tg), crystallization temperature (Tc), and overall thermal stability. The findings reveal that the stability does not consistently follow a single pattern with K2O doping. Notably, the Li1.6K0.4PbP2O7 glass exhibits the greatest stability. The addition of K2O led to a reduction of the density and an increase in the molar volume of the system. These observations align with FTIR results, which reveal that introducing additional potassium ions results in longer bond lengths and weaker bonds. The spectroscopic study was supported by Raman spectroscopy. Post-annealing XRD analysis revealed the presence of distinct crystalline phases that differed according to the K2O content The structure of the various phosphate groups in the synthesized materials after annealing was also analyzed using Fourier Transform Infrared (FTIR) spectroscopy. Moreover, dielectric studies were conducted over a range of frequencies, and the presence of the relaxation phenomenon as well as the influence of potassium content on dielectric features have been evidenced.