Charting Impact: HKU’s 2025 Performance in Essential Science Indicators (ESI)
— by Juliana Lau
Following our analyses of the University of Hong Kong’s (HKU) research performance using Essential Science Indicators (ESI) published in 2024, this year’s review consolidates the latest trends using ESI’s rolling 10‑year window and bi‑monthly updates. We focus on HKU ranking in ESI, citation standing within fields, and growth in Highly Cited Papers and Hot Papers. We align our methodology with earlier posts to support year‑over‑year comparisons[1].
HKU ranking in Highly Cited Institutions
In 2025, HKU ranks in the top 10% by total citations received among the Highly Cited Institutions in the below 5 research fields, making HKU the top 1‰[2]. Notably, HKU has been listed as Highly Cited Institutions in 21 of 22 research fields, and HKU’s position rose in 14 research fields compared with last year. This highlights HKU’s growing influence in different research fields.
| Research Field | Rank of HKU | Total Number of Highly Cited Institutions |
| Clinical Medicine | 177 | 6754 |
| Social Sciences, General | 65 | 2407 |
| Engineering | 87 | 2787 |
| Environment/ Ecology | 147 | 2066 |
| Microbiology | 63 | 803 |
Highly Cited Papers
The numbers of Highly Cited Papers in the ESI 22 fields are given in the table below. This year, HKU continues to expand its portfolio of Highly Cited Papers, reaching a new high in 2025 across multiple fields with 1449 papers. Clinical Medicine remains the leading contributor with 398 papers, followed by Social Sciences, General with 130, Engineering with 120, and Physics with 117. Notable increases of Highly Cited Papers appear in Computer Science (31→45), Neuroscience & Behavior (18→24), Social Sciences, General (103→130). Building on the steady upward trajectory since 2021, HKU’s growth is broad-based.
Figure 1: Number of Highly Cited Papers authored by HKU researchers in year 2021 to 2025
Hot papers
In the 3rd bi-monthly period of 2025, HKU authors contributed 53 Hot Papers across 15 ESI fields, with standout concentrations in Clinical Medicine with 14 papers, followed by Social Sciences, General with 8 papers, and both Geosciences and Computer Science with 5 each. The high counts in Clinical Medicine reflect strong early visibility for HKU’s recent clinical research outputs.
Figure 2: Number of Hot Papers authored by HKU researchers in the 3rd bi-monthly period of 2025
Key takeaways
We can see a strong cross‑field presence of HKU research. HKU continues to be listed as a Highly Cited Institution (top 1% by citations in field) across most of the 22 ESI fields, echoing the broad disciplinary footprint reported in our 2023 and 2024 posts. The count of HKU Highly Cited Papers (top 1% by field and year) continues its upward curve observed since 2021, led by Clinical Medicine and supported by growth in multiple research fields. Clinical Medicine, Social Sciences, General, Engineering, Environment/Ecology, and Microbiology remain among HKU’s strongest fields, placing the university in the top decile of Highly Cited Institutions (top 1‰), indicating high standing within a competitive group of institutions.
Notes
- ESI data covers a rolling 10-year period and includes bimonthly updates to rankings and citation counts. This blog post compares the 3rd bi-monthly dataset release from 2021 to 2025, each covering a 10-year-and-6-month period. For example, the 3rd bi-monthly dataset release in 2025 covers data from January 1, 2015 to June 30, 2025.
- Top 1‰ institution is derived by the citation rank of an institution within all Highly Cited Institutions listed on ESI in the same research field. For example, there are 6754 Highly Cited Institutions in Clinical Medicine in 2025. Institution rank of 675 or above would be regarded as top 1‰ institution in the field.
