Cross-national comparisons of cognitive test scores are a subject of debate because measurement instruments are predominantly developed and validated on Western participants. Establishing between-nations measurement invariance (MI) is necessary to meaningfully interpret differences in intelligence test scores between countries. IRT-based approaches are particularly suitable for testing MI, because they allow for item-level examination of measurement properties and assessment of between-group test unidimensionality. The Three-Dimensional Cubes Test (3DC) is a Rasch-calibrated measure of visual processing that was originally developed for use in Germanophone countries. Prior studies showed (partial) MI across Austrian, Singaporean and US samples, supporting its suitability for cross-national comparisons. In this study, we compared spatial task performance from N = 300+ undergraduate students, respectively, from Austria and the Philippines. We used a stepwise approach to establish MI by examining Rasch-homogeneity within as well as across countries. Likelihood-ratio tests indicated model fit for all but one item, enabling a comparison of the mean person parameters after excluding the misfitting item. Our results indicate a very large mean difference between the groups (Cohen’s d = 2.22), with the Austrian sample scoring higher than the Filipino sample. The present data clearly show the necessity of establishing measurement invariance for a meaningful cross-national comparison of cognitive subdomains.