Let the process \(x^{\alpha}\) describe the evolution of the instantaneous spot interest rate under the risk-adjusted martingale measure \(Q^{x}\) and the dynamics of \(x^{\alpha}\) is expressed by \[ dx^{\alpha}_{t}=\mu(x^{\alpha}_{t};\alpha) dt+ \sigma(x^{\alpha}_{t};\alpha) dW_{t}, \] where \(\alpha\in \mathbb{R}^{n}, n\geq 1\) is a vector of parameters; \(W_{t}\) is a standard Brownian motion. If we denote by \(P^{x}(t,T)\) the price at time \(t\) of zero-coupon bond maturing at \(T\) with unit face value, then \[ P^{x}(t,T)= {\mathbf E}^{x} \left[\exp \Biggl\{-\int_{t}^{T} x^{\alpha}_{s} ds \Biggr\}|F_{t}^{x} \right], \] where \({\mathbf E}^{x}\) denotes the expectation under risk-adjusted martingale measure \(Q^{x}\). Let us assume that there exists an explicit real function \(\Pi^{x}\), defined on a suitable subset of \(\mathbb{R}^{n+3}\), such that \(P^{x}(t,T)=\Pi^{x}(t,T,x^{\alpha}_{t};\alpha)\). The authors propose the new instantaneous short rate defined by \(r_{t}=x_{t}+\phi(t;\alpha), t\geq 0\), where \(\phi\) is a deterministic function. The price at time \(t\) of zero-coupon bond maturing at \(T\) with unit face value in this new model is \[ P(t,T)=\exp \Biggl\{-\int_{t}^{T}\phi(s;\alpha) ds \Biggr\}\Pi^{x}(t,T,r_{t}-\phi(t;\alpha);\alpha). \] The zero-coupon bond option price in the new model is described also. Extensions of the Vasicek model, Cox-Ingersoll-Ross model, Dethan model and “exponential Vasicek” model are studied.