<p>Hyperspectral image super-resolution (HSI-SR) aims to reconstruct high-resolution hyperspectral images from low-resolution inputs, which is particularly challenging due to the high dimensionality and complex spatial-spectral correlations inherent in hyperspectral data. While attention-based approaches have shown potential by enhancing contextual feature extraction, most existing methods either focus on local neighborhoods or treat spatial and spectral information independently, leading to limited modeling of long-range dependencies and suboptimal multi-scale feature fusion. Furthermore, conventional U-Net architectures are not tailored to address the unique redundancies and limited training data often observed in hyperspectral imaging tasks. To address these issues, we propose Cs_Unet, a cross-range self-attention approach for single HSI-SR built upon the U-Net framework. The core of proposed model integrates cross-range spatial self-attention (CSA) and cross-range spectral self-attention (CSE) to explicitly capture associations between distant spatial locations and spectral bands. Our cross-range spatial-spectral self-attention interaction (CAI) module processes spatial and spectral features in parallel and fuses them for improved image reconstruction. Additionally, we incorporate a cross-range grouped convolution upsampling (GCUc) module at the top of the U-Net to enhance information flow and leverage progressive upsampling. By embedding these modules within the U-Net architecture, our model achieves effective multi-scale feature fusion and exploits both global context and fine-grained details. Extensive experiments demonstrate that Cs_Unet outperforms other competitors in terms of both visual fidelity and quantitative metrics.</p>