How to determine character encoding in Hyper SQL database
HSQLDB stores text data as Unicode. You can verify that by opening the .script file for the database and looking at the data.

For example, for a table with a row containing "Montréal" the .script file contains

CREATE MEMORY TABLE PUBLIC.TABLE1(ID INTEGER PRIMARY KEY,TEXTCOL VARCHAR(50))
...
INSERT INTO TABLE1 VALUES(1,'Montr\u00e9al')


where \u0039 is the Unicode code point for the letter é.