AbstractThe dependence of mechanical and water‐holding properties of soy protein gels upon their structures was examined. Gels varying in extent of network formation were prepared by heating 20% paste of the isolated soy protein (ISP) containing L‐cysteine hydrochloride (CySH) which has an ability to cleave intermolecular disulfide bonds. A rapid decrease in gel hardness and cohesiveness was observed with the increase in added amount of CySH up to 2.5 times 10‐5mole/g ISP, and then a gradual decrease to 5.0 times 10‐5mole/g ISP. The changes in these mechanical parameters appeared to depend on the degree of the network formation interpreted from the solubility changes of gels in the phosphate buffer containing 6 M urea. The relaxation time, estimated by compression stress relaxation, was also dependent on the degree of the network formation, while the modulus of elasticity was hardly affected. On the other hand, there was an inverse correlation between the NMR line width of the water proton and expressible water by the pressure method as an index of water‐holding properties of the gel; the broader the former, the lesser the latter. The change in the water‐holding capacity estimated from expressible water was also associated with that in the degree of the network formation. This confirms that both mechanical and water‐holding properties of the gel are qualitatively governed by the extent of the structure formation controlled by the intermolecular di