Ab initio post UHF, DFT, CASSCF and semiempirical INDO calculations were carried out for one- and two-dimensional poly(phenylenmethylene) in order to elucidate variations of the effective exchange integrals with molecular connectivity, cluster size and hole (electron) doping. It was shown that the ferromagnetic effective exchange integrals by UCCSD(T) and DFT/4-31G are about 400 cm(-1) for m-phenylene bis(methylene). The high-spin ground states of hole-doped polycarbenes were also studied, indicating a possibility of obtaining the high T-c organic ferrimagnets induced by the one electron transfer between polycarbene and spacer (electron donor or acceptor).