The strain energy of phenanthrene was derived to be (4.9 +/- 2.8) kJ (.) mol(-1), on the basis of the latest standard enthalpies of formation of polycyclic aromatic hydrocarbons. This strain energy agrees well with those estimated from a semi-empirical calculation and from the basicity in hydrogen fluoride solution. The calculation again confirmed the standard enthalpy of formation of phenanthrene, Delta(f)H(0)(g) (201.7 +/- 2.9) kJ (.) mol(-1) at T = 298.15 K, which was determined by Nagano (J. Chem. Thermodyn. 34 (2002) 377-383). The coupling constant J(4,5) in H-1-n.m.r. spectrum of phenanthrene in CDCl3 solution was determined to be 0.55 Hz, which indicates no significant through-space coupling between the 4- and 5-hydrogens. (C) 2003 Elsevier Ltd. All rights reserved.