In this paper, we report magnetostriction measurements, (λ₁₀₀) on Fe-rich Fe–Al alloys and Fe₅₀Co₅₀ as functions of temperature from 77 K to room temperature (RT). From these measurements and elastic constant (c′) measurements, the tetragonal magnetoelastic coupling constants (b₁’s) were calculated. Significant differences were found between our RT measurements and earlier magnetostriction measurements for the higher Al concentration alloys (16.6%, 21.5%, 26.3% Al) and the Fe₅₀Co₅₀ alloy. Reminiscent of the temperature dependence of λ₁₀₀ for pure Fe, magnetostriction changes with temperature are minimal for Fe–Al alloys having the disordered bcc (A2)structure (x<19% Al). In contrast, the alloy possessing the ordered (D0₃) structure shows an anomalous decrease in magnetostriction in λ₁₀₀ with decreasing temperature. For the Fe–Al alloy system, the magnetoelastic coupling constant, ∣b₁∣, exhibits a peak at room temperature maximizing at 16.6% Al with a value of 12.3 MJ/m³. For Fe₅₀Co₅₀, ∣b₁∣ was calculated to be ∼ 34 MJ/m³ at room temperature.