For the first time, a method for calculating formulas of homologous series of chemical compounds of the systems (Aa+ – Bb+ – Cc–) and {Zn2+ – Ge4+ – P3–} in a generalized form is presented. The calculation is confirmed by the literature experimentally obtained compounds: thirteen compounds of the system (Na+ – Ti4+ – O2–), seven – systems (Li+ – Ti4+ – O2–), five – systems (K+ – V5+ – – O2–), eight – systems (Ba2+ – Cu2+ – O2–). Homological series in (Aa+ – Bb+ – Cc–) have the following generalized form: A{t – k·r + nr – r)bcBracC{t – k·r + nr)ab and AtbcB{r – k·t + nt – t}acC (r – k·t + nt)ab.