Two series of binary mixtures nBCB-nTPCHB and nCPB-nTPCHB were ivestigated by the thermomicroscopic method. A strong enhancement of the smectic phase region with simultanous appearance of the reentrant nematic phase on the phase diagrams is observed. The appearance of the reentrant nematic phase confirm that the smectic A(d) phase is formed in these binary mixtures. It was shown that the length of the aliphatic chain of both component plays an important role on the induction of the smectic A(d) and nematic reentrant phase.