Some investigations on the titanium-containing (～5% Ti) and higher cobolt content (～34% Co) permanent magnet alloy recently developed upon the basis of the composition of Alnico 5 are reported in this paper. It is shown that superior permanent magnetic properties may be obtained by means of isothermal magnetic treatment as compared with those obtained by controlled cooling rate treatment, confirming the experience of Koch et al. It has been found that the coercive force is very sensitive to the temperature of isothermal magnetic treatment. The structural states of isothermally-magnetically treated specimens were investigated by means of electron microscopy and other means. The results indicate that different conditions of prior isothermal magnetic treatment lead to states of different dispersion and morphology of the a′-phase, and hence to different permanent magnetic properties. The experimentally determined C-curve of γ1-phase shows that the precipitation of the γ1-phase is very rapid. Careful metallographic examination has revealed that the so called ar-phase is actually heterogeneous. The experimentally established quantitative relationship between the permanent magnet properties of the alloy and the content of the "ar-phase" clearly demonstrates the detrimental effect of the latter on the former.