Abstract The standard (p∘ = 0.1 MPa) molar energies of combustion in oxygen, at T = 298.15 K, of two crystalline bis(N,N-diethylthioureas) R(CONHCSNEt2)2: pyridine-2,6-dicarbonyl-bis(N,N-diethylthiourea), R = pyridyl, abbreviated as (bis-py-DETU), and adipoyl-dicarbonyl-bis(N,N-diethylthiourea), R = (CH2)4, abbreviated as (bis-ad-DETU), were measured by rotating bomb calorimetry so, the standard molar enthalpies of formation of both compounds, in their crystalline phase, were derived. Compound - Δ c U m ∘ ( cr ) - Δ f H m ∘ ( cr ) kJ · mol - 1 kJ · mol - 1 Pyridine-2,6-dicarbonyl-bis(N,N-diethylthiourea) [bis-py-DETU] 11027.1 ± 5.2 425.2 ± 5.6 Adipoyl-dicarbonyl-bis(N,N-diethylthiourea) [bis-ad-DETU] 11124.6 ± 5.7 644.4 ± 6.1 Furthermore, the energetics of the title compounds were studied by means of density functional theory calculations at the B3LYP/ 6-311G(dp) level of theory.