The post-main-sequence evolution of massive stars remains a challenging area of study, with many aspects still poorly understood. By investigating the pulsational behavior of evolved massive blue supergiants (BSGs), which occupy instability region at the top of the HR diagram, we can gain insights into their internal structure and verify existing evolutionary models. I combined various methods of frequency analysis to investigate the variability of the BSG rho Leonis. I leverage long-term spectroscopic monitoring data collected at the Tartu Observatory, complemented by space photometry obtained from the K2 and TESS missions.